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  • 1.
    Alfredsson, Ylfi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Kjeldgaard, Lisbeth
    O´Shea, J. N.
    Theobald, J.
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Phase and molecular orientation in H2Pc on conducting glass: characterization of two deposition methods2005In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 493, no 1-2, p. 13-19Article in journal (Refereed)
    Abstract [en]

    In this study, metal-free phthalocyanine has been deposited on a conducting glass surface by two methods: by spreading the molecular powder directly on the substrate in air and by vapor sublimation under ultra-high vacuum conditions (evaporation). The films have been characterized by means of core level X-ray Photoemission Spectroscopy, X-ray Absorption Spectroscopy (XAS) and Ultra Violet and Visible absorption spectroscopy (UV-Vis). Our results show that the two deposition methods produce molecular overlayers in different polymorphic phases; the UV-Vis measurements indicate that the film obtained by powder deposition is of x-phase type whereas sublimation leads to an α-polymorph structure. The XAS results show that in the powder deposited film the molecules are mainly oriented parallel to the surface. This is opposite to the case of the vapor deposited film, where the molecules mainly are oriented orthogonal to the surface.

  • 2.
    Alfredsson, Ylvi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Brena, Barbara
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Kjeldgaard, Lisbeth
    Nyberg, Mats
    Luo, Yi
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Electronic structure of a vapor-deposited metal-free phthalocyanine thin film2005In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 122, no 21, p. 214723-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of a vapor-sublimated thin film of metal-free phthalocyanine(H2Pc) is studied experimentally and theoretically. An atom-specific picture of the occupied and unoccupied electronic states is obtained using x-ray-absorption spectroscopy (XAS), core- and valence-level x-ray photoelectron spectroscopy (XPS), and density-functional theory (DFT) calculations. The DFT calculations allow for an identification of the contributions from individual nitrogen atoms to the experimental N1sXAS and valence XPS spectra. This comprehensive study of metal-free phthalocyanine is relevant for the application of such molecules in molecular electronics and provides a solid foundation for identifying modifications in the electronic structure induced by various substituent groups.

  • 3.
    Alfredsson, Ylvi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Kjeldgaard, Lisbeth
    O'Shea, James
    Theobald, J
    Bao, Zhuo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sandell, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Phase and molecular orientation in metal-free phthalocyanine films on conducting glass: Characterization of two deposition methods2005In: Thin Solid Films, Vol. 493, no 1-2, p. 13-19Article in journal (Refereed)
  • 4.
    Berner, Simon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Biela, Sarah
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Ledung, Greger
    Gogoll, Adolf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry, Organic Chemistry I.
    Bäckvall, Jan-E.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Oscarsson, Sven
    Activity boost of a biomimetic oxidation catalyst by immobilization onto a gold surface2006In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 244, no 1, p. 86-91Article in journal (Refereed)
    Abstract [en]

    Thiol-functionalized cobalt porphyrins were used as a model system for investigating catalytic activity in homogeneous and heterogeneous oxidation catalysis. Self-assemble monolayers of thiol-functionalized cobalt porphyrins were prepared on a gold surface and served as heterogenous catalysts. These immoblilized molecules prevented the strong inactivation observed for their homogeneous congener. As a result, the turnover number per molecule in heterogeneous catalysis was at least 100 times higher than that of the corresponding homogeneous catalyst. It is atypical for a heterogenized catalyst to outperform its homogeneous congener. The properties of the molecular layers were characterized on the molecular level by means of X-ray photoelectorn spectroscopy (XPS) and scanning tunneling microscopy (STM). The results demonstrate that the performance of these biomimetic catalysts can be dramatically improved if the catalyst arangement can be controlled on the molecular level.

  • 5.
    Berner, Simon
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Lidbaum, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Ledung, G.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Schiessling, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Gelius, Ulrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics I.
    Bäckwall, J. E.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Oscarsson, Sven
    Electronic and structural studies of immobilized thiol-derivatized cobalt porphyrins on gold surfaces2007In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 253, no 18, p. 7540-7548Article in journal (Refereed)
    Abstract [en]

    The immobilisation of thiol-derivatized cobalt porphyrins on gold surfaces has been studied in detail by means of combined scanning tunnelling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). S-thioacetyl has been used as a protective group for the thiol. Different routes for deprotection of the acetyl groups were performed in acidic and in basic conditions. The results show the formation of monolayer films for the different preparation schemes. The immobilisation of the molecules on the gold surface takes place through the thiol-linkers by the formation of multiple thiolate bonds. In the case of layers formed with protected porphyrins approximately 60% of the linkers are bonded to the gold surface whereas for deprotected layers the amount of bonded linkers is increased up to about 80%. STM measurements revealed that the molecules arrange in a disordered overlayer and do not exhibit mobility on the gold surface. Annealing experiments have been performed in order to test the stability of the porphyrin layers. Disordered patterns have been observed in the STM images after annealing at T = 400 °C. XPS revealed that the sulphur content disappeared completely after annealing at T = 180 °C and that the molecules did undergo significant modifications.

  • 6.
    Bernes, E.
    et al.
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Fronzoni, G.
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Stener, M.
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Guarnaccio, A.
    ISM CNR, Inst Struct Matter, Tito, PZ, Italy.;ISM CNR, Inst Struct Matter, Trieste, Italy..
    Zhang, T.
    Beijing Inst Technol BIT, Sch Informat & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China.;Uppsala Univ, Dept Phys & Astron, SE-75120 Uppsala, Sweden..
    Grazioli, C.
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Basovizza, Italy..
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Coreno, M.
    ISM CNR, Inst Struct Matter, Tito, PZ, Italy.;ISM CNR, Inst Struct Matter, Trieste, Italy..
    de Simone, M.
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Basovizza, Italy..
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Toffoli, D.
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    S 2p and P 2p Core Level Spectroscopy of PPT Ambipolar Material and Its Building Block Moieties2020In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, no 127, p. 14510-14520Article in journal (Refereed)
    Abstract [en]

    The near-edge X-ray absorption fine structure (NEXAFS and X-ray photoelectron (XP) spectra of gas-phase 2,8-bis-(diphenylphosphoryl)dibenzo[b,d]thiophene (PPT) and triphenylphosphine oxide (TPPO) have been measured at the S and P L-II,L-III-edge regions. The time-dependent density functional theory (TDDFT) based on the relativistic two-component zeroth-order regular approximation approach has been used to provide an assignment of the experimental spectra, giving the contribution of the spin-orbit splitting and of the molecular-field splitting to the sulfur and phosphor binding energies. Computed XP and NEXAFS spectra agree well with the experimental measurements. In going from dibenzothiophene and TPPO to PPT, the nature of the most intense S 2p and P 2p NEXAFS features are preserved; this trend suggests that the electronic and geometric behaviors of the S and P atoms in the two building block moieties are conserved in the more complex system of PPT. This work enables us to shed some light onto the structure of the P-O bond, a still highly debated topic in the chemical literature. Since the S 2p and P 2p NEXAFS intensities provide specific information on the higher-lying localized sigma*(C-S) and sigma*(P-O) virtual MOs, we have concluded that P 3d AOs are not involved in the formation of the P-O bond. Moreover, the results support the mechanism of negative hyperconjugation, by showing that transitions toward sigma*(P-O) states occur at lower energies with respect to those toward it pi*(P-O) states.

  • 7.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Ahmadi, Sareh
    KTH.
    Grazioli, Cesare
    University of Trieste.
    Bouvet, Marcel
    University of Bourgone.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Witkowski, Nadine
    Universite de Pierre et Marie Curie.
    Adsorption and Molecular Orientation of Lutetium bi-Phthalocyanine Adlayers on Pristine Si(100)2x1 SurfaceManuscript (preprint) (Other academic)
    Abstract [en]

    A combined photoelectron spectroscopy (PES), X-ray absorption spectroscopy (XAS)

    and scanning tunneling microscopy (STM) study has been performed to follow the

    change in adsorption geometry and to characterize the adsorbate interaction with the

    substrate for dierent thicknesses of lutetium biphthalocyanine (LuPc2) adlayers on

    pristine Si(100)-2x1 reconstructed stepped surface. A shift to lower binding energies

    with increasing thickness has been shown. The STM results showed clustering of

    LuPc2 starting from submonolayer coverages and two distinct adsorption types have

    been identied. The STM and PES results have been linked together to propose two

    dierent adsorption types involving a stronger and weaker interaction with the Si

    dangling bonds. A change in average angle of molecules with respect to the normal

    of the surface for increasing thicknesses has been seen from the XAS measurements,

    leading to disordered layers for thicker films.

  • 8.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Brumboiu, Iulia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Totani, Roberta
    University of L'Aquila.
    Grazioli, Cesare
    University of Trieste.
    Shariati Nilsson, Masumeh Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Herper, Heike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ressel, B
    Univ Nova Gorica, Ajdovscina 5270, Slovenia.
    de Simone, Monica
    Lozzi, Luca
    University of L'Aquila.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Atomic Contributions to the Valence Band Photoelectron Spectra of Metal-free, Iron and Manganese Phthalocyanines2015In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, E-ISSN 1873-2526, Vol. 205, p. 92-97Article, review/survey (Other academic)
    Abstract [en]

    The present work reports a photoelectron spectroscopy study of the low-energy region of the valence band of metal-free phthalocyanine (H2Pc) compared with those of iron phthalocyanine (FePc) and manganese phthalocyanine (MnPc). We have analysed in detail the atomic orbital composition of the valence band both experimentally, by making use of the variation in photoionization cross-sections with photon energy, and theoretically, by means of density functional theory. The atomic character of the Highest Occupied Molecular Orbital (HOMO), reflected on the outermost valence band binding energy region, is different for MnPc as compared to the other two molecules. The peaks related to the C 2p contributions, result in the HOMO for H2Pc and FePc and in the HOMO-1 for MnPc as described by the theoretical predictions, in very good agreement with the experimental results. The DFT simulations, discerning the atomic contribution to the density of states, indicate how the central metal atom interacts with the C and N atoms of the molecule, giving rise to different partial and total density of states for these three Pc molecules.

  • 9.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Ahmadi, S.
    Materialfysik, KTH-Electrum.
    Grazioli, C.
    CNR-IOM, Laboratorio TASC.
    Bouvet, M.
    Institut de Chimie Moléculaire de l’Université de Bourgogne.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Mårtensson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Witkowski, N.
    Institut des Nanosciences de Paris, UPMC.
    When the Grafting of Double Decker Phthalocyanines on Si(100)-2 × 1 Partly Affects the Molecular Electronic Structure2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 26, p. 14270-14276Article in journal (Refereed)
    Abstract [en]

    A combined X-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and density functional theory (DFT) study has been performed to characterize the adsorbate interaction of lutetium biphthalocyanine (LuPc2) molecules on the Si(100)-2 × 1 surface. Large molecule–substrate adsorption energies are computed and are found to compete with the molecule–molecule interactions of the double decker molecules. A particularly good matching between STM images and computed ones confirms the deformation of the molecule upon the absorption process. The comparison between DFT calculations and XP spectra reveals that the electronic distribution in the two plateaus of the biphthalocyanine are not affected in the same manner upon the adsorption onto the silicon surface. This finding can be of particular importance in the implementation of organic molecules in hybrid devices.

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  • 10.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Boudet, S.
    Zhang, T.
    Ahmadi, S.
    Grazioli, C.
    Bouvet, M.
    Rusz, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Witkowski, N.
    Experimental and theoretical study of electronic structure of lutetium bi-phthalocyanine2013In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 138, no 23, p. 234701-Article in journal (Refereed)
    Abstract [en]

    Using Near Edge X-Ray Absorption Fine Structure (NEXAFS) Spectroscopy, the thickness dependent formation of Lutetium Phthalocyanine (LuPc2) films on a stepped passivated Si(100)2x1 reconstructed surface was studied. Density functional theory (DFT) calculations were employed to gain detailed insights into the electronic structure. Photoelectron spectroscopy measurements have not revealed any noticeable interaction of LuPc2 with the H-passivated Si surface. The presented study can be considered to give a comprehensive description of the LuPc2 molecular electronic structure. The DFT calculations reveal the interaction of the two molecular rings with each other and with the metallic center forming new kinds of orbitals in between the phthalocyanine rings, which allows to better understand the experimentally obtained NEXAFS results. 

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  • 11.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Totani, Roberta
    University of L'Aquila.
    Grazioli, Cesare
    University of Trieste.
    de Simone, Monica
    Coreno, Marcello
    Kivimäki, Antti
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lozzi, Luca
    University of L'Aquila.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Characterization of Gas Phase of Iron Phthalocyanine with X-ray Photoelectron and Absorption Spectroscopies2015In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 252, no 6, p. 1259-1265Article in journal (Refereed)
    Abstract [en]

    Despite the numerous studies dedicated to phthalocyanine molecules adsorbed on surfaces, in monolayer or thin film, very few works have been focused on the characterization of vapors of these molecules. In this article we present the C 1s, N 1s and Fe 2p photoemission results as well as N K-edge X-ray absorption data of iron phthalocyanine (FePc) in gas phase. Presented comparison of X-ray photoelectron spectroscopy and X-ray absorption spectroscopy spectra of FePc films show a great similarity with the gas phase results, confirming the molecular character of thick films. The Fe2p photoemission spectrum of the gas phase FePc, shown for the first time, can be considered as a fingerprint of the Fe(II) ionic state of the central metal of the iron phthalocyanine. The performed multiplet calculations for describing the Fe 2p XP spectrum indicate 3Eg (a1g2eg32g1) state as the most probable ground state for thick film of iron phthalocyanine.

  • 12.
    Bidermane, Ieva
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Latvels, Janis
    Riga Technical University.
    Pudzs, Kaspars
    University of Latvia.
    Bouvet, Marcel
    University of Bourgone.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Witkowski, Nadine
    Universite de Pierre et Marie Curie.
    Formation of Self-organized bi-Layer of LuPc2 Molecules on Gold (111) SurfaceManuscript (preprint) (Other academic)
  • 13. Brena, Barbara
    et al.
    Luo, Yi
    Nyberg, Mats
    Carniato, Stephane
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Alfredsson, Ylvi
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Equivalent core-hole time-dependent density functional theory calculations of carbon 1s shake-up states of phthalocyanine2004In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 70, no 19, p. 195214-Article in journal (Refereed)
    Abstract [en]

    The shake-up transition energies of the carbon 1s photoelectron spectrum of metal-free phthalocyanine (H2Pc) have been calculated by means of time-dependent density functional theory, for which an equivalent core approximation is adopted. Model calculations for the C 1s shake-up states of benzene are in excellent agreement with the latest experimental results. The complex C 1s shake-up structures associated with the aromatic and pyrrole carbons in the phthalocyanine are computed, as well as their ionization potentials. They allow us to determine the origin of the anomalous intensity ratio between the pyrrole and benzene carbons in a high resolution C 1s photoelectron spectrum measured for a H2Pc film, as due to a benzene-related shake-up contribution, hidden under the pyrrole main intensity feature.

  • 14.
    Brena, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    de Simone, Monica
    Coreno, Marcello
    Tarafder, Kartick
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Feyer, Vitaly
    Banerjee, Rudra
    Gothelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Oppeneer, Peter M.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Valence-band electronic structure of iron phthalocyanine: An experimental and theoretical photoelectron spectroscopy study2011In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 134, no 7, p. 074312-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of iron phthalocyanine (FePc) in the valence region was examined within a joint theoretical-experimental collaboration. Particular emphasis was placed on the determination of the energy position of the Fe 3d levels in proximity of the highest occupied molecular orbital (HOMO). Photoelectron spectroscopy (PES) measurements were performed on FePc in gas phase at several photon energies in the interval between 21 and 150 eV. Significant variations of the relative intensities were observed, indicating a different elemental and atomic orbital composition of the highest lying spectral features. The electronic structure of a single FePc molecule was first computed by quantum chemical calculations by means of density functional theory (DFT). The hybrid Becke 3-parameter, Lee, Yang and Parr (B3LYP) functional and the semilocal 1996 functional of Perdew, Burke and Ernzerhof (PBE) of the generalized gradient approximation (GGA-) type, exchange-correlation functionals were used. The DFT/B3LYP calculations find that the HOMO is a doubly occupied pi-type orbital formed by the carbon 2p electrons, and the HOMO-1 is a mixing of carbon 2p and iron 3d electrons. In contrast, the DFT/PBE calculations find an iron 3d contribution in the HOMO. The experimental photoelectron spectra of the valence band taken at different energies were simulated by means of the Gelius model, taking into account the atomic subshell photoionization cross sections. Moreover, calculations of the electronic structure of FePc using the GGA+U method were performed, where the strong correlations of the Fe 3d electronic states were incorporated through the Hubbard model. Through a comparison with our quantum chemical calculations we find that the best agreement with the experimental results is obtained for a U-eff value of 5 eV.

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  • 15.
    Brumboiu, Iulia Emilia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Totani, Roberta
    de Simone, Monica
    Coreno, Marcello
    Grazioli, Cesare
    Lozzi, Luca
    Herper, Heike C
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Elucidating the 3d Electronic Configuration in Manganese Phthalocyanine2014In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 118, no 5, p. 927-932Article in journal (Refereed)
    Abstract [en]

    To shed light on the metal 3d electronic structure of manganese phthalocyanine, so far controversial, we performed photoelectron measurements both in the gas phase and as thin film. With the purpose of explaining the experimental results, three different electronic configurations close in energy to one another were studied by means of density functional theory. The comparison between the calculated valence band density of states and the measured spectra revealed that in the gas phase the molecules exhibit a mixed electronic configuration, while in the thin film, manganese phthalocyanine finds itself in the theoretically computed ground state, namely, the b2g1eg3a1g1b1g0 electronic configuration.

  • 16.
    Ciavardini, Alessandra
    et al.
    Univ Roma La Sapienza, Dipartimento Chim & Tecnol Farmaco, Ple A Moro 5, I-00185 Rome, Italy;Univ Roma Tor Vergata, Dipartimento Sci & Tecnol Chim, Via Ric Sci, I-00133 Rome, Italy;CERIC ERIC, Basovizza Area Sci Pk, I-34149 Trieste, Italy.
    Coreno, Marcello
    ISM CNR, Basovizza Area Sci Pk, I-34149 Trieste, Italy;Elettra Sincrotrone Trieste, Ss 14,Km 163,5, I-34149 Trieste, Italy.
    Callegari, Carlo
    Elettra Sincrotrone Trieste, Ss 14,Km 163,5, I-34149 Trieste, Italy.
    Spezzani, Carlo
    Elettra Sincrotrone Trieste, Ss 14,Km 163,5, I-34149 Trieste, Italy.
    De Ninno, Giovanni
    Elettra Sincrotrone Trieste, Ss 14,Km 163,5, I-34149 Trieste, Italy;Univ Nova Gor, Lab Quantum Opt, Vipayska 11c, SI-5270 Ajdovscina, Slovenia.
    Ressel, Barbara
    Elettra Sincrotrone Trieste, Ss 14,Km 163,5, I-34149 Trieste, Italy;Univ Nova Gor, Lab Quantum Opt, Vipayska 11c, SI-5270 Ajdovscina, Slovenia.
    Grazioli, Cesare
    IOM CNR, Lab TASV, Basovizza SS-14,Km 163-5, I-34012 Trieste, Italy.
    de Simone, Monica
    IOM CNR, Lab TASV, Basovizza SS-14,Km 163-5, I-34012 Trieste, Italy.
    Kivimäki, Antti
    IOM CNR, Lab TASV, Basovizza SS-14,Km 163-5, I-34012 Trieste, Italy;Lund Univ, MAX 4 Lab, POB 118, SE-22100 Lund, Sweden.
    Miotti, Paolo
    IFN CNR, Padova Res Unit, Via Trasea 7, I-35131 Padua, Italy.
    Frassetto, Fabio
    IFN CNR, Padova Res Unit, Via Trasea 7, I-35131 Padua, Italy.
    Poletto, Luca
    IFN CNR, Padova Res Unit, Via Trasea 7, I-35131 Padua, Italy.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Fornarini, Simonetta
    Univ Roma La Sapienza, Dipartimento Chim & Tecnol Farmaco, Ple A Moro 5, I-00185 Rome, Italy.
    Pezzella, Marco
    Univ Roma La Sapienza, Dipartimento Chim, Ple A Moro 5, I-00185 Rome, Italy.
    Bodo, Enrico
    Univ Roma La Sapienza, Dipartimento Chim, Ple A Moro 5, I-00185 Rome, Italy.
    Piccirillo, Susanna
    Univ Roma Tor Vergata, Dipartimento Sci & Tecnol Chim, Via Ric Sci, I-00133 Rome, Italy.
    Ultra-Fast-VUV Photoemission Study of UV Excited 2-Nitrophenol2019In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 123, no 7, p. 1295-1302Article in journal (Refereed)
    Abstract [en]

    The initial deactivation pathways of gaseous 2-nitrophenol excited at 268 nm were investigated by time-resolved photoelectron spectroscopy (TRPES) with femtosecond-VUV light, produced by a monochromatized high harmonic generation source. TRPES allowed us to obtain new, valuable experimental information about the ultrafast excited-state dynamics of 2-nitrophenol in the gas phase. In accord with recent ab initio on-the-fly nonadiabatic molecular dynamic simulations, our results validate the occurrence of an ultrafast intersystem crossing leading to an intermediate state that decays on a subpicosecond time scale with a branched mechanisms. Two decay pathways are experimentally observed. One probably involves proton transfer, leading to the most stable triplet aci-form of 2-nitrophenol; the second pathway may involve OH rotation. We propose that following intersystem crossing, an ultrafast fragmentation channel leading to OH or HONO loss could also be operative.

  • 17. Eriksson, Kristofer
    et al.
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Backvall, Jan-E.
    Oscarsson, Sven
    Performance of a biomimetic oxidation catalyst immobilized on silica particles2013In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 303, p. 16-21Article in journal (Refereed)
    Abstract [en]

    A biomimetic oxidation catalyst, cobalt porphyrin with thiol linkers, was chemically conjugated to silica particles and utilized in the oxidation of hydroquinone to benzoquinone. The cobalt porphyrin/silica particle catalyst was characterized with Inductively Coupled Plasma (ICP) and X-ray Photoelectron Spectroscopy (XPS). The catalytic performance of the cobalt porphyrin molecules was compared to previous results for the same catalyst grafted to a gold surface and on silicon wafers. The measured catalytic activity, after background correction, was 100 times higher than that of its homogeneous counterpart, 10 times higher than that on a silicon wafer, and almost the same as that on a gold surface. The turnover frequency rates after 400 h are still comparable with initial rates reported for homogeneous porphyrins and salophens, whereas the use of particles as support increases the active surface area, which removes the limitations for scale-up associated with the previously used silicon wafers and gold surfaces.

  • 18.
    Guarnaccio, Ambra
    et al.
    Ist Struttura Mat, ISM CNR, Trieste, Italy..
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Beijing Inst Technol BIT, Sch Informat & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China.
    Grazioli, Cesare
    Sincrotrone Trieste, Lab TASC, IOM CNR, I-34149 Trieste, Basovizza, Italy..
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Coreno, Marcello
    Ist Struttura Mat, ISM CNR, Trieste, Italy..
    de Simone, Monica
    Sincrotrone Trieste, Lab TASC, IOM CNR, I-34149 Trieste, Basovizza, Italy..
    Fronzoni, Giovanna
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Toffoli, Daniele
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Bernes, Elisa
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    PPT Isolated Molecule and Its Building Block Moieties Studied by C 1s and O 1s Gas Phase X-ray Photoelectron and Photoabsorption Spectroscopies2020In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 124, no 18, p. 9774-9786Article in journal (Refereed)
    Abstract [en]

    The present study is focused on the comprehensive gas phase electronic structure characterization of 2,8-bis-(diphenylphosphoryl)-dibenzo[b,d]thiophene (PPT), a promising ambipolar phosphorescent host material recently introduced in organic light-emitting diodes (OLEDs). This molecular system can be considered ideally formed by two diphenylphosphine oxide (dPPO) moieties functionalizing the small dibenzothiophene (DBT) core. PPT is characterized by high triplet energy and is known as good vacuum sublimable electron transporting material for blue OLEDs. The triphenyl phosphine oxide (TPPO) molecule has been chosen as the model compound of the dPPO groups in PPT. A combined experimental and theoretical study by density functional theory of the gas phase electronic structure of TPPO and PPT has been performed through X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy measured at the carbon and oxygen is regions. The study represents a detailed characterization of the impact of the single building blocks on the electronic structure of the whole PPT molecule. Moreover, it confirms that the phosphine oxide groups act as breaking points of the pi-conjugation between the DBT core of PPT and the outer groups, leaving the electronic structures of the compound practically matching those of the central DBT moiety.

  • 19. Kivimaeki, A.
    et al.
    Norman, P.
    Coreno, M.
    de Simone, M.
    Grazioli, C.
    Totani, R.
    Ressel, B.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Use of two-dimensional photoelectron spectroscopy in the decomposition of an inner-shell excitation spectrum broadened by super-Coster-Kronig decay2013In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 88, no 6, p. 062502-Article in journal (Refereed)
    Abstract [en]

    The Ge 3p core excitation spectrum of the n-butylgermane molecule only reveals two peaks, whereas the rest of the fine structure is obscured due to the large lifetime broadenings of core-excited states. A two-dimensional presentation of resonant photoemission spectra allows us to observe some other resonances. The interpretation of experimental results is supported by ab initio calculations conducted at the four-component relativistic level of theory with full account made for spin-orbit interactions already in the zeroth-order Hamiltonian.

  • 20.
    Lanzilotto, Valeria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Sapienza Univ Rome, Dept Chem, Ple Aldo Moro 8, I-00185 Rome, Italy.;CNR, Ist Officina Mat, IOM, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy..
    Grazioli, Cesare
    CNR, Ist Officina Mat, IOM, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy..
    Stredansky, Matus
    CNR, Ist Officina Mat, IOM, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy.;Univ Trieste, Dept Phys, Via A Valeria 2, I-34127 Trieste, Italy.;Beijing Inst Technol BIT, Sch Informat & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Beijing Inst Technol BIT, Sch Informat & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Schio, Luca
    CNR, Ist Officina Mat, IOM, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy..
    Goldoni, Andrea
    Elettra Sincrotrone Trieste SCpA, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy..
    Floreano, Luca
    CNR, Ist Officina Mat, IOM, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy..
    Motta, Alessandro
    Sapienza Univ Rome, Dept Chem, Ple Aldo Moro 8, I-00185 Rome, Italy.;Consortium INSTM, Via G Giusti 9, I-50121 Florence, Italy..
    Cossaro, Albano
    CNR, Ist Officina Mat, IOM, Basovizza SS 14,Km 163-5, I-34149 Trieste, Italy.;Univ Trieste, Dept Chem & Pharmaceut Sci, Via Giorgieri 1, I-34127 Trieste, Italy..
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Tailoring surface-supported water-melamine complexes by cooperative H-bonding interactions2021In: Nanoscale Advances, E-ISSN 2516-0230, Vol. 3, no 8, p. 2359-2365Article in journal (Refereed)
    Abstract [en]

    The water-splitting photo-catalysis by carbon nitride heterocycles has been the subject of recent theoretical investigations, revealing a proton-coupled electron transfer (PCET) reaction from the H-bonded water molecule to the CN-heterocycle. In this context, a detailed characterization of the water-catalyst binding configuration becomes mandatory in order to validate and possibly improve the theoretical modeling. To this aim, we built a well-defined surface-supported water/catalyst interface by adsorbing water under ultra-high vacuum (UHV) conditions on a monolayer of melamine grown on the Cu(111) surface. By combining X-ray photoemission (XPS) and absorption (NEXAFS) spectroscopy we observed that melamine adsorbed onto copper is strongly tilted off the surface, with one amino group dangling to the vacuum side. The binding energy (BE) of the corresponding N 1s component is significantly higher compared to other N 1s contributions and displays a clear shift to lower BE as water is adsorbed. This finding along with density functional theory (DFT) results reveals that two adjacent melamine molecules concurrently work for stabilizing the H-bonded water-catalyst complex: one melamine acting as a H-donor via the amino-N (NHMIDLINE HORIZONTAL ELLIPSISOHH) and another one as a H-acceptor via the triazine-N (C = NMIDLINE HORIZONTAL ELLIPSISHOH).

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  • 21.
    Lanzilotto, Valeria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Silva, Jose Luis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Stredansky, Matus
    Univ Trieste, Dept Phys, Via A Valerio 2, I-34127 Trieste, Italy;CNR, IOM, Lab TASC, Basovizza SS-14,Km 163-5, I-34149 Trieste, Italy.
    Grazioli, Cesare
    CNR, ISM, Unit LD2, Basovizza SS-14,Km 163-5, I-34149 Trieste, Italy.
    Simonov, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin GmbH, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany.
    De Simone, Monica
    CNR, IOM, Lab TASC, Basovizza SS-14,Km 163-5, I-34149 Trieste, Italy.
    Coreno, Marcello
    CNR, ISM, Unit LD2, Basovizza SS-14,Km 163-5, I-34149 Trieste, Italy.
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Spectroscopic Fingerprints of Intermolecular H-Bonding Interactions in Carbon Nitride Model Compounds2018In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 53, p. 14198-14206Article in journal (Refereed)
    Abstract [en]

    The effect of intermolecular H-bonding interactions on the local electronic structure of N-containing functional groups (amino group and pyridine-like N) that are characteristic of polymeric carbon nitride materials p-CN(H), a new class of metal-free organophotocatalysts, was investigated. Specifically, the melamine molecule, a building block of p-CN(H), was characterized by X-ray photoelectron (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecule was studied as a noninteracting system in the gas phase and in the solid state within a H-bonded network. With the support of DFT simulations of the spectra, it was found that the H-bonds mainly affect the N1s level of the amino group, leaving the N1s level of the pyridine-like N mostly unperturbed. This is responsible for a reduction of the chemical shift between the two XPS N1s levels relative to free melamine. Consequently, N K-edge NEXAFS resonances involving the amino N1s level also shift to lower photon energies. Moreover, the solid-state absorption spectra showed significant modification/quenching of resonances related to transitions from the amino N1s level to sigma* orbitals involving the NH2 termini.

  • 22.
    Lanzilotto, Valeria
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Silva, Jose Luis
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Stredansky, Matuš
    Department of Physics University of Trieste.
    Grazioli, Cesare
    CNR-ISM, Istituto di Struttura della Materia (LD2 Unit).
    Simonov, Konstantin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Giangrisostomi, Erika
    Institute Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin GmbH.
    Ovsyannikov, Ruslan
    Institute Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin GmbH.
    de Simone, Monica
    CNR-IOM, Istituto Officina dei Materiali (Laboratorio TASC).
    Coreno, Marcello
    CNR-ISM, Istituto di Struttura della Materia (LD2 Unit).
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Spectroscopic Fingerprints of Carbon Nitride Functional Groups Locked-up in Intermolecular H-bonding InteractionsIn: Chemistry: A European Journal, ISSN 0947-6539Article in journal (Refereed)
    Abstract [en]

    We have investigated the effect of intermolecular H- bonding interactions on the local electronic structure of N- functionalities, amino group and pyridine-like N, which are characteristic of a new class of metal-free polymeric photo-catalysts named graphitic carbon nitrides, g-C3N4. Specifically, we have performed a characterization of the melamine molecule, a building block of g-C3N4, combining X-ray photoemission (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The molecule has been studied in the gas phase, as non-interacting system, and in the solid state within a hydrogen bonded network. With the support of density functional theory (DFT) simulations of the spectra, we have found that the H-bonds mainly affect the N 1s level of the amino group, leaving the N 1s level of the pyridine-like N mostly unperturbed. This fact is responsible for a reduction of the chemical shift between the two XPS N 1s levels, compared to the free melamine. Consequently, N K-edge NEXAFS resonances involving the amino N 1s level also shift to lower photon energies. Moreover, the solid state absorption spectra have shown strong modification/quenching of resonances related with transitions from the amino N 1s level towards σ*orbitals involving the -NH2 terminations. 

  • 23.
    Luder, Johann
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    de Simone, Monica
    Totani, Roberta
    Coreno, Marcello
    Grazioli, Cesare
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    The electronic characterization of biphenylene-Experimental and theoretical insights from core and valence level spectroscopy2015In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 142, no 7, article id 074305Article in journal (Refereed)
    Abstract [en]

    In this paper, we provide detailed insights into the electronic structure of the gas phase biphenylene molecule through core and valence spectroscopy. By comparing results of X-ray Photoelectron Spectroscopy (XPS) measurements with Delta SCF core-hole calculations in the framework of Density Functional Theory (DFT), we could decompose the characteristic contributions to the total spectra and assign them to non-equivalent carbon atoms. As a difference with similar molecules like biphenyl and naphthalene, an influence of the localized orbitals on the relative XPS shifts was found. The valence spectrum probed by photoelectron spectroscopy at a photon energy of 50 eV in conjunction with hybrid DFT calculations revealed the effects of the localization on the electronic states. Using the transition potential approach to simulate the X-ray absorption spectroscopy measurements, similar contributions from the non-equivalent carbon atoms were determined from the total spectrum, for which the slightly shifted individual components can explain the observed asymmetric features.

  • 24.
    Luder, Johann
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Comparison of van der Waals corrected and sparse-matter density functionals for the metal-free phthalocyanine/gold interface2014In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 89, no 4, p. 045416-Article in journal (Refereed)
    Abstract [en]

    In this paper, we report a systematic study on the effect of different van der Waals dispersion correction methods in conjunction with Density Functional Theory on the adsorption characteristics of a monolayer of metal-free phthalocyanine on Au(111). The chosen dispersion corrections were DFT-D2, the Tkatchenko-Scheffler method with and without self-consistent screening, and four sparse-matter density functionals. A comparison among different dispersion corrections was performed and the results are related to available experimental scanning tunnel microscopy and x-ray standing-wave measurements for similar molecules on Au(111). We found that the Tkatchenko-Scheffler method as well as a sparse-matter density functional which employs the exchange potential of optB86b and the nonlocal correlation of Dion describe the adsorbed system, e. g., electronic and geometric structure with an adsorption distance of 3.3 angstrom, reasonably well within moderate computational costs.

  • 25.
    Lüder, Johann
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Ottosson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Many-body effects and excitonic features in 2D biphenylene carbon2016In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, no 2, article id 024702Article in journal (Refereed)
    Abstract [en]

    The remarkable excitonic effects in low dimensional materials in connection to large binding energies of excitons are of great importance for research and technological applications such as in solar energy and quantum information processing as well as for fundamental investigations. In this study, the unique electronic and excitonic properties of the two dimensional carbon network biphenylene carbon were investigated with GW approach and the Bethe-Salpeter equation accounting for electron correlation effects and electron-hole interactions, respectively. Biphenylene carbon exhibits characteristic features including bright and dark excitons populating the optical gap of 0.52 eV and exciton binding energies of 530 meV as well as a technologically relevant intrinsic band gap of 1.05 eV. Biphenylene carbon's excitonic features, possibly tuned, suggest possible applications in the field of solar energy and quantum information technology in the future.

  • 26.
    Nilson, Katharina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Schiessling, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Scanning tunneling microscopy study of metal-free phthalocyanine monolayer structures on graphite2007In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 127, no 11, p. 114702-Article in journal (Refereed)
    Abstract [en]

    Low temperature scanning tunneling microscopy (STM) studies of metal-free phthalocyanine (H2Pc) adsorbed on highly oriented pyrolytic graphite (HOPG) have shown ordered arrangement of molecules for low coverages up to 1 ML. Evaporation of H2Pc onto HOPG and annealing of the sample to 670 K result in a densely packed structure of the molecules. Arrangements of submonolayer, monolayer, and monolayer with additional adsorbed molecules have been investigated. The high resolution of our investigations has permitted us to image single molecule orientation. The molecular plane is found to be oriented parallel to the substrate surface and a square adsorption unit cell of the molecules is reported. In addition, depending on the bias voltage, different electronic states of the molecules have been probed. The characterized molecular states are in excellent agreement with density functional theory ground state simulations of a single molecule. Additional molecules adsorbed on the monolayer structures have been observed, and it is found that the second layer molecules adsorb flat and on top of the molecules in the first layer. All STM measurements presented here have been performed at a sample temperature of 70 K.

  • 27.
    Nilson, Katharina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Åhlund, John
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Shariati, Masumeh-Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Schiessling, Joachim
    Palmgren, Pål
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Hennies, Franz
    Huismans, Y
    Evangelista, F
    Rudolf, Petra
    Göthelid, Mats
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Potassium-intercalated H2Pc films: Alkali-induced electronic and geometrical modifications2012In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 137, no 4, p. 044708-Article in journal (Refereed)
    Abstract [en]

    X-ray spectroscopy studies of potassium intercalated metal-free phthalocyanine multilayers adsorbed on Al(110) have been undertaken. Photoelectron spectroscopy measurements show the presence of several charge states of the molecules upon K intercalation, due to a charge transfer from the alkali. In addition, the comparison of valence band photoemission spectra with the density functional theory calculations of the density of states of the H2Pc anion indicates a filling of the formerly lowest unoccupied molecular orbital by charge transfer from the alkali. This is further confirmed by x-ray absorption spectroscopy (XAS) studies, which show a decreased density of unoccupied states. XAS measurements in different experimental geometries reveal that the molecules in the pristine film are standing upright on the surface or are only slightly tilted away from the surface normal but upon K intercalation, the molecular orientation is changed in that the tilt angle of the molecules increases.

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  • 28. O´Shea, J. N.
    et al.
    Swarbrick, J. C.
    Nilson, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Brena, Barbara
    Luo, Yi
    Dhanak, V. R.
    Molecular ordering in isonicotinic acid on rutile TiO2 (110) investigated with valence band photoemission2004In: The Journal of Chemical Physics, Vol. 121, p. 10203-Article in journal (Refereed)
  • 29.
    Puglia, Carla
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Technology, Department of Engineering Sciences, Electronics.
    Bennich, P
    Department of Materials Science. Technology, Department of Engineering Sciences, Electronics.
    Hasselstrom, J
    Ribbing, Carolina
    Department of Materials Science. Technology, Department of Engineering Sciences, Electronics. Fasta tillståndets elektronik.
    Bruhwiler, PA
    Nilsson, A
    Li, ZY
    Mårtensson, Nils
    Technology, Department of Engineering Sciences, Electronics.
    Core level spectroscopy study of N-2 adsorbed on (2x2)K/graphite1998In: SURFACE SCIENCE, ISSN 0039-6028, Vol. 414, no 1-2, p. 118-130Article in journal (Other scientific)
    Abstract [en]

    We report a study of N-2/(2 x 2)K/graphite at 25 K using X-ray photoemission, X-ray absorption (XAS), ultraviolet photoemission, autoionization and Auger spectroscopies. At this temperature me found that N-2 physisorbs. Comparisons with the physisorbed sy

  • 30.
    Roberta, Totani
    et al.
    Department of physical and chemical sciences, university of L'Aquila, Italy.
    Cesare, Grazioli
    CNR-ISM, Italy.
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ieva, Bidermane
    Institute Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz Zentrum Berlin.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Monica, de Simone
    CNR-IOM, Italy.
    Marcello, Coreno
    CNR-ISM, Italy.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Luca, Lozzi
    Department of physical and chemical sciences, university of L'Aquila, Italy.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Electronic structure investigations of biphenylene filmsArticle in journal (Refereed)
    Abstract [en]

    Photoelectron Spectroscopy (PES) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy have been used to investigate the occupied and empty density of states of biphenylene films of different thicknesses, deposited onto a Cu(111) crystal. The obtained results have been compared to previous gas phase spectra and single molecule density functional theory (DFT) calculations to get insights into the possible modification of the molecular electronic structure in the film induced by the adsorption on a surface. Furthermore, NEXAFS measurements allowed characterizing the variation of the molecular arrangement with the film thickness and helped to clarify the substrate- molecule interaction. 

  • 31.
    Shariati, Masumeh-Nina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Bidermane, Ieva
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Ahmadi, Sareh
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Palmgren, Pål
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Photoelectron and Absorption Spectroscopy Studies of Metal-Free Phthalocyanine on Au(111): Experiment and Theory2013In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 117, no 14, p. 7018-7025Article in journal (Refereed)
    Abstract [en]

    The adsorption of monolayers and multilayers of metal-free phthalocyanine molecules on the Au(111) (root 3 x 22) reconstructed surface has been investigated by X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). Our results for the monolayer show that the molecules are arranged tightly onto the surface with their molecular plane parallel to it. In addition, the X-ray absorption spectra of the monolayer have been modeled by density functional theory, which could enlighten new aspect of the interaction between molecules and substrate. The XAS results evidence that also in the multilayer the molecules keep the orientation with the molecular plane parallel to the surface. These results are discussed in the framework of moleculemolecule/moleculeadsorbate interactions.

  • 32.
    Teng, Zhang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Iulia, Brumboiu
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Cesare, Grazioli
    University of Trieste.
    Valeria, Lanzilotto
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Erika, Giangrisostomi
    Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin.
    Ruslan, Ovsyannikov
    Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin.
    Sassa, Yasmine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ieva, Bidermane
    Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin.
    Matija, Stupar
    University of Nova Gorica, Slovenia.
    Monica, de Simone
    CNR-IOM, Italy.
    Marcello, Coreno
    CNR-ISM, Italy.
    Barbara, Ressel
    University of Nova Gorica, Slovenia.
    Maddalena, Pedio
    CNR-IOM, Italy.
    Petra, Rudolf
    Zernike Institute for Advanced Materials, University of Groningen, Netherland.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Exploring the electronic structure of CoPc by photoemission and absorption spectroscopyManuscript (preprint) (Other academic)
    Abstract [en]

    Photoelectron spectroscopy  and X-ray absorption spectroscopy were used to investigate the occupied and empty density of states of cobalt phthalocyanine (CoPc) in the gas phase and in thin films of different thicknesses, deposited onto a Au (111) single crystal. The comparison between experimental gas phase results and density functional theory single molecule simulations confirmed that the CoPc ground state is correctly described by the 2A1g electronic configuration. Moreover, the atomic character of the highest occupied molecular orbital of CoPc was addressed by performing photon energy dependent valence photoemission spectroscopy experiments on both CoPc gas phase and film samples. Our results clearly show that the highest occupied molecular orbital is derived only from the organic ligand, with mainly contribution from the carbon atoms. Multiplet ligand field theory was employed to simulate the Co L edge X-ray absorption spectroscopy results.

  • 33. Toffoli, D.
    et al.
    Guarnaccio, A.
    Grazioli, C.
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    de Simone, M.
    Coreno, M.
    Santagata, A.
    D’Auria, M.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Bernes, E.
    Stener, M.
    Fronzoni, G.
    Electronic Structure Characterization of a Thiophene Benzo-Annulated Series of Common Building Blocks for Donor and Acceptor Compounds Studied by Gas Phase Photoelectron and Photoabsorption Synchrotron Spectroscopies2018In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 122, no 44, p. 8745-8761Article in journal (Refereed)
    Abstract [en]

    The near-edge x-ray-absorption fine-structure (NEXAFS) and Xray photoelectron spectroscopy (XPS) spectra of benzo[b]thiophene (BBT) and dibenzothiophene (DBT) in the gas phase have been measured at the carbon Kedge and sulfur L-II,L-III-edge regions. The assignment of the spectral features has been provided by theoretical calculations based on density functional theory (DFT) and its time-dependent generalization (TDDFT) in the linear response regime. Observed trends in computed C 1s and S 2p ionization potentials (IPs) have been rationalized in terms of both the inductive effects due to the presence of S and the increased pi-electrons delocalization arising from the benzoannulation process. The analysis of the NEXAFS carbon K-edge and sulfur L-II,L-III-edge regions regions provided information on both low-lying delocalized virtual pi orbitals, and higher-lying localized sigma*(C-S) states. The evolution of the NEXAFS carbon K-edge spectral features along the series thiophene (T) and derivatives, BBT and DBT, is informative of a stabilizing effect due to increased aromaticity. This effect is however more pronounced in going from T to BBT compared to the introduction of a second annulated phenyl ring in DBT. The nature of the most intense sulfur L-II,L-III-edge NEXAFS spectral features is instead conserved along the series reflecting thus the localized nature of the virtual states involved in the S 2p core-excitation process.

  • 34.
    Totani, R.
    et al.
    Univ Aquila, Dept Phys & Chem Sci, Via Vetoio, I-67100 Coppito, Italy.;Univ Pierre & Marie Curie Paris VI, UMR CNRS 7197, Lab Reactivite Surface, Tour 43-44 3eme etage,Case 178,4 Pl Jussieu, F-75005 Paris, France..
    Grazioli, C.
    Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy.;CNR, ISM, SS 14 km 163-5, I-34149 Trieste, Basovizza, Italy..
    Zhang, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Bidermane, I.
    Helmholtz Zentrum Berlin, Inst Methods & Instrumentat Synchrotron Rad Res, Albert Einstein St 15, D-12489 Berlin, Germany..
    Lüder, J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    de Simone, M.
    CNR, IOM, SS 14 Km 163-5, I-34149 Trieste, Basovizza, Italy..
    Coreno, M.
    CNR, ISM, SS 14 km 163-5, I-34149 Trieste, Basovizza, Italy..
    Brena, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Lozzi, L.
    Univ Aquila, Dept Phys & Chem Sci, Via Vetoio, I-67100 Coppito, Italy..
    Puglia, C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Electronic structure investigation of biphenylene films2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, no 5, article id 054705Article in journal (Refereed)
    Abstract [en]

    Photoelectron Spectroscopy (PS) and Near-Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy have been used to investigate the occupied and empty density of states of biphenylene films of different thicknesses, deposited onto a Cu(111) crystal. The obtained results have been compared to previous gas phase spectra and single molecule Density Functional Theory (DFT) calculations to get insights into the possible modification of the molecular electronic structure in the film induced by the adsorption on a surface. Furthermore, NEXAFS measurements allowed characterizing the variation of the molecular arrangement with the film thickness and helped to clarify the substrate-molecule interaction. Published by AIP Publishing.

  • 35.
    Ugolotti, Aldo
    et al.
    Univ Milano Bicocca, Dept Mat Sci, I-20125 Milan, Italy..
    Lanzilotto, Valeria
    Ist Off Mat, IOM CNR, I-34149 Trieste, Italy.;Sapienza Univ Roma, Dipartimento Chim, I-00185 Rome, Italy.;Univ Trieste, Dipartimento Sci Chim & Farmaceut, Via Licio Giorgieri 1, I-34127 Trieste, Italy..
    Grazioli, Cesare
    Ist Off Mat, IOM CNR, I-34149 Trieste, Italy..
    Floreano, Luca
    Ist Off Mat, IOM CNR, I-34149 Trieste, Italy.;Ist Off Mat, IOM CNR, I-34149 Trieste, Italy..
    Manuel Zamalloa-Serrano, Jorge
    Inst Ciencia Mat Madrid ICMM CSIC, ESISNA Grp, Madrid 28049, Spain..
    Stredansky, Matus
    Ist Off Mat, IOM CNR, I-34149 Trieste, Italy.;Univ Trieste, Dept Phys, I-34127 Trieste, Italy..
    Zhang, Teng
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Beijing Inst Technol BIT, Sch Integrated Circuits & Elect, MIIT Key Lab Lowdimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    de Simone, Monica
    Ist Off Mat, IOM CNR, I-34149 Trieste, Italy..
    Ferraro, Lorenzo
    Univ Milano Bicocca, Dept Mat Sci, I-20125 Milan, Italy..
    Coreno, Marcello
    Ist Struttura Mat, ISM CNR, I-34149 Trieste, Italy..
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Di Valentin, Cristiana
    Univ Milano Bicocca, Dept Mat Sci, I-20125 Milan, Italy..
    In-Plane Hydrogen Bonds and Out-of-Plane Dipolar Interactions in Self-Assembled Melem Networks2023In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 127, no 23, p. 11307-11316Article in journal (Refereed)
    Abstract [en]

    Melem(2,6,10-triamino-s-heptazine) is the building block of melon,a carbon nitride (CN) polymer that is proven to produce H-2 from water under visible illumination. With the aim of bringingadditional insight into the electronic structure of CN materials,we performed a spectroscopic characterization of gas-phase melem andof a melem-based self-assembled 2D H-bonded layer on Au(111) by meansof ultraviolet and X-ray photoemission spectroscopy (UPS, XPS) andnear-edge X-ray absorption fine structure (NEXAFS) spectroscopy. Inparallel, we performed density functional theory (DFT) simulationsof the same systems to unravel the molecular charge density redistributioncaused by the in-plane H-bonds. Comparing the experimental resultswith the spectroscopic DFT simulations, we can correlate the inducedcharge accumulation on the N-amino atoms to the red-shiftof the corresponding N 1s binding energy (BE) and of the N-amino 1s -> LUMO+n transitions. Moreover, when introducing a supportingAu(111) surface in the computational simulations, we observe a molecule-substrateinteraction that almost exclusively involves the out-of-plane molecularorbitals, leaving those engaged in the in-plane H-bonded network ratherunperturbed.

  • 36.
    Witkowski, Nadine
    et al.
    Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Lüder, Johann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Natl Sun Yat Sen Univ, Dept Mat & Optoelect Sci, Kaohsiung 80424, Taiwan.
    Bidermane, Ieva
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Farronato, Mattia
    Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Prevot, Geoffroy
    Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, 4 Pl Jussieu, F-75005 Paris, France.
    Bouvet, Marcel
    Univ Bourgogne Franche Comte, Inst Chim Mol, Univ Bourgogne, CNRS,UMR 6302, F-21078 Dijon, France.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Grafting, self-organization and reactivity of double-decker rare-earth phthalocyanine2019In: Journal of Porphyrins and Phthalocyanines, ISSN 1088-4246, E-ISSN 1099-1409, Vol. 23, no 11-12, p. 1523-1534Article in journal (Refereed)
    Abstract [en]

    Unveiling the interplay of semiconducting organic molecules with their environment, such as inorganic materials or atmospheric gas, is the first step to designing hybrid devices with tailored optical, electronic or magnetic properties. The present article focuses on a double-decker lutetium phthalocyanine known as an intrinsic semiconducting molecule, holding a Lu ion in its center, sandwiched between two phthalocyanine rings. Carrying out experimental investigations by means of electron spectroscopies, X-ray diffraction and scanning probe microscopies together with advanced ab initio computations, allows us to unveil how this molecule interacts with weakly or highly reactive surfaces. Our studies reveal that a molecule-surface interaction is evidenced when molecules arc deposited on bare silicon or on gold surfaces together with a charge transferred from the substrate to the molecule, affecting to a higher extent the lower ring of the molecule. A new packing of the molecules on gold surfaces is proposed: an eclipse configuration in which molecules are flat and parallel to the surface, even for thick films of several hundreds of nanometers. Surprisingly, a robust tolerance of the double-decker phthalocyanine toward oxygen molecules is demonstrated, leading to weak chemisorption of oxygen below 100 K.

  • 37.
    Zhang, Teng
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. BIT, Sch Informat & Elect, Beijing 100081, Peoples R China.
    Brumboiu, I. E.
    Royal Inst Technol KTH, Dept Theoret Chem & Biol, S-10691 Stockholm, Sweden;Korea Adv Inst Sci & Technol, Dept Chem, Daejeon 34141, South Korea.
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Univ Roma La Sapienza, Dept Chem, Piazzale Aldo Moro 5, I-00185 Rome, Italy.
    Grazioli, C.
    Sincrotrone Trieste, Lab TASC, CNR, IOM, Trieste, Italy.
    Guarnaccio, A.
    CNR, ISM, Tito, Pz, Italy;Trieste LD2 Unit, Trieste, Italy.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Coreno, M.
    CNR, ISM, Tito, Pz, Italy;Trieste LD2 Unit, Trieste, Italy.
    de Simone, M.
    Sincrotrone Trieste, Lab TASC, CNR, IOM, Trieste, Italy.
    Santagata, A.
    CNR, ISM, Tito, Pz, Italy;Trieste LD2 Unit, Trieste, Italy.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Electronic structure modifications induced by increased molecular complexity: from triphenylamine to m-MTDATA2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 32, p. 17959-17970Article in journal (Refereed)
    Abstract [en]

    The starburst pi-conjugated molecule 4,4 ',4 ''-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (C57H48N4, m-MTDATA), based on triphenylamine (TPA) building blocks, is widely used in optoelectronic devices due to its good electron-donor characteristics. The electronic structure of m-MTDATA was investigated for the first time in the gas phase by means of PhotoElectron Spectroscopy (PES) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The combination of Density Functional Theory (DFT) calculations with the experimental spectra provides a comprehensive description of the molecular electronic structure. Moreover, by comparing the results with previous TPA measurements, we could shed light on how the electronic structure evolves when the molecular size is increased. We found that the C 1s photoelectron spectra of m-MTDATA and TPA are similar, due to the balance of the counter-acting effects of the electronegativity of the N atoms and the delocalization of the amine lone-pair electrons. In contrast, the increased number of N atoms (i.e. N lone pairs) in m-MTDATA determines a three-peak feature in the outermost valence binding energy region with strong contributions by the N 2p(z) orbitals. We also obtained a decrease of the HOMO-LUMO gap for m-MTDATA, which points to improved electron donating properties of m-MTDATA with respect to TPA.

  • 38.
    Zhang, Teng
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Brumboiu, I. E.
    Royal Inst Technol, Dept Theoret Chem & Biol, SE-10691 Stockholm, Sweden..
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Luder, J.
    Natl Univ Singapore, Dept Mech Engn, Singapore 117575, Singapore..
    Grazioli, C.
    ISM CNR, Trieste Unit LD2, Basovizza AREA Sci Pk, I-34149 Trieste, Italy..
    Giangrisostomi, E.
    Helmholtz Zentrum Berlin, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Ovsyannikov, R.
    Helmholtz Zentrum Berlin, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Sassa, Yasmine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Bidermane, I.
    Helmholtz Zentrum Berlin, Inst Methods & Instrumentat Synchrotron Radiat Re, Albert Einstein Str 15, D-12489 Berlin, Germany..
    Stupar, M.
    Univ Nova Gorica, Dept Phys, Vipavska Cesta 11C, Ajdovscina 5270, Slovenia..
    de Simone, M.
    CNR IOM, SS 14 Km 163,5, I-34149 Trieste, Italy..
    Coreno, M.
    ISM CNR, Trieste Unit LD2, Basovizza AREA Sci Pk, I-34149 Trieste, Italy..
    Ressel, B.
    Univ Nova Gorica, Dept Phys, Vipavska Cesta 11C, Ajdovscina 5270, Slovenia..
    Pedio, M.
    CNR IOM, SS 14 Km 163,5, I-34149 Trieste, Italy..
    Rudolf, P.
    Univ Groningen, Zernike Inst Adv Mat, Nijenborgh 4, NL-9747 AG Groningen, Netherlands..
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Conclusively Addressing the CoPc Electronic Structure: A Joint Gas-Phase and Solid-State Photoemission and Absorption Spectroscopy Study2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 47, p. 26372-26378Article in journal (Refereed)
    Abstract [en]

    The occupied and empty densities of states of cobalt phthalocyanine (CoPc) were investigated by photoelectron and X-ray absorption spectroscopies in the gas phase and in thin films deposited on a Au(111) surface. The comparison between the gas-phase results and density functional theory single-molecule simulations confirmed that the CoPc ground state is correctly described by the (2)A(1g) electronic configuration. Moreover, photon-energy-dependent valence photoemission spectra of both the gas phase and thin film confirmed the atomic character of the highest occupied molecular orbital as being derived from the organic ligand, with dominant contributions from the carbon atoms. Multiplet ligand-field theory was employed to simulate the Co L-edge X-ray absorption spectroscopy results.

  • 39.
    Zhang, Teng
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Brumboiu, Iulia E.
    KTH Royal Institute of Technology, Department of Theoretical Chemistry and Biology & Korea Advanced Institute of Science and Technology (KAIST), Department of Chemistry.
    Grazioli, Cesare
    ISM-CNR, Trieste LD2 Unit, Italy.
    Guarnaccio, Ambra
    ISM-CNR, Tito Scalo (Pz), Italy.
    Coreno, Marcello
    ISM-CNR, Trieste LD2 Unit, Italy.
    de Simone, Monica
    IOM-CNR, Laboratorio TASC, Sincrotrone Trieste, Basovizza, Trieste, Italy.
    Santagata, Antonio
    ISM-CNR, Tito Scalo (Pz), Italy.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Lone-Pair Delocalization Effects within Electron Donor Molecules: The Case of Triphenylamine and Its Thiophene-Analog2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 31, p. 17706-17717Article in journal (Refereed)
    Abstract [en]

    Triphenylamine (TPA) and its thiophene-analog, N,N-diphenyl-2-thiophenamine (DPTA), are both well-known as electron-donating molecules implemented in optoelectronic devices such as organic solar cells and LEDs. Comprehensive valence and core level photoelectron spectroscopy, as well as near edge X-ray absorption spectroscopy (NEXAFS), measurements have been performed on gas phase TPA and DPTA. The experimental results have been compared to density functional theory calculations, providing a detailed description of the molecular electronic structure. Specifically, the C 1s photoelectron lines of both TPA and DPTA were resolved in the different C atom contributions and their binding energies explained as the result of two counter-acting effects: (1) the electronegativity of the nitrogen atom (and sulfur atom in DPTA) and (2) the the N (and S in DPTA) lone-pair electrons. In addition, the C K-edge NEXAFS spectrum of DPTA reveals that the lowest unoccupied molecular orbital (LUMO) energy position is affected differently if the core hole site is on the phenyl compared to the thiophene ring. The electron-donating properties of these two molecules are largely explained by the significant contribution of the N lone-pair electrons (p(z)) to the highest occupied molecular orbital. The contribution to the LUMO and to the empty density of states of the sulfur of the thiophene ring in DPTA explains the better performance of donor-pi-acceptor molecules containing this moiety and implemented in photoenergy conversion devices.

  • 40.
    Zhang, Teng
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Brumboiu, Iulia E.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics.
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Grazioli, Cesare
    ISM-CNR, Trieste LD2 Unit, Italy.
    Guarnaccio, Ambra
    ISM-CNR, Tito Scalo (Pz), Italy.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ševčíková, Klára
    Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague, Czech Republic.
    Coreno, Marcello
    ISM-CNR, Trieste LD2 Unit, Italy.
    de Simone, Monica
    IOM-CNR, Laboratorio TASC, Sincrotrone Trieste, Basovizza, Trieste, Italy.
    Santagata, Antonio
    ISM-CNR, Tito Scalo (Pz), Italy.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Electronic Structure Study of Free and Adsorbed m-MTDATAManuscript (preprint) (Other academic)
    Abstract [en]

    The starburst p-conjugated molecule based on triphenylamine (TPA) building block, 4,4',4" -Tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine (m-MTDATA), is widely used in optoelectronic devices due to its electron-donating properties. The electronic structure of m-MTDATA was investigated in the gas-phase and when deposited in thin films on a Au(111) surface by means of PhotoElectron Spectroscopy (PES) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. Density Functional Theory (DFT) calculations were compared to the experimental gas-phase results, providing a comprehensive description of the molecular electronic structure. Moreover, the results were compared with previous TPA measurements, shedding light on the electronic structure modification due to the increased molecular complexity.  Similar to TPA, but more complex, the binding energy of the C 1s photoelectron line of m-MTDATA results from the balance of two counter-acting effects: (1) the electronegativity of the N atoms and (2) the delocalization of lone-pair electrons of the nitrogen. Compared to TPA, the outermost valence PE spectrum of m-MTDATA shows a 3-peak feature with N 2pz character and a lowering of the binding energy of the HOMO. When adsorbed on Au(111),  the changes observed in PES and NEXAFS spectra with respect to the free molecules,  can be explained by a significant modification of m-MTDATA molecular and electronic structure, due to the molecule-substrate interaction.

  • 41.
    Zhang, Teng
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Brumboiu, Iulia E.
    Royal Institute of Technology (KTH), Department of Theoretical Chemistry and Biology.
    Lanzilotto, Valeria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Grazioli, Cesare
    ISM-CNR, Trieste LD2 Unit, Italy.
    Guarnaccio, Ambra
    ISM-CNR, Tito Scalo (Pz), Italy.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ševčíková, Klára
    Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University in Prague, Czech Republic.
    Coreno, Marcello
    ISM-CNR, Trieste LD2 Unit, Italy.
    de Simone, Monica
    IOM-CNR, Laboratorio TASC, Sincrotrone Trieste, Basovizza, Trieste, Italy.
    Santagata, Antonio
    ISM-CNR, Tito Scalo (Pz), Italy.
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    X-ray Spectroscopy Investigations of TPA/Au(111): Charge Redistribution via Core Exitation?Manuscript (preprint) (Other academic)
    Abstract [en]

    Triphenylamine (TPA) is a well-known electron donor molecule largely used in photovoltaics. In this article we analyze the electronic structure modifications due to the adsorption of the molecules at a monolayer coverage on a Au(111) surface. Only a weak interaction was observed between the TPA and the gold during the adsorption process, being impossible to get more than 1ML coverage at room temperature. The characterizations have been performed by core and valence Photoelectron Spectroscopy (PES) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy. The results were compared with our previous investigations on free TPA, and theoretical models were used to explain the changes of the electronic structure due to the adsorption on the metallic gold surface. The calculation confirms the weak interaction between the adsorbed TPA and the Au(111), with only a slight change of the twisting angle of the TPA phenyl rings. The resulting adsorption geometry can be used to explain the broadening of the C 1s PES line with respect to the gas-phase results and the expected absence of angle dependence in the C K-edge NEXAFS. However, a significant modification was observed in the N K-edge NEXAFS spectra of TPA/Au(111), showing a new pre-edge feature due to transitions involving out-of-plane orbitals. This pre-edge feature is ascribed to the interaction between the molecules and the surface, having a different character and energy position than the pre-edge observed for free TPA. A model, considering a TPA+ cation formed by a charge redistribution process between the adsorbate and the surface valence states seems to give a qualitative explanation of this pre-edge intensity. Since our calculations predict only a weak interaction between the TPA molecules and the gold surface, we propose that such a charge redistribution happens in the core-excited state created by photon absorption.

  • 42.
    Zhang, Teng
    et al.
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Grazioli, Cesare
    Sincrotrone Trieste, IOM CNR, Lab TASC, I-34149 Trieste, Italy..
    Guarnaccio, Ambra
    Ist Struttura, ISM, CNR, I-85050 Tito, Pz, Italy..
    Brumboiu, Iulia Emilia
    Pohang Univ Sci & Technol POSTECH, Dept Chem, Pohang 37673, South Korea..
    Lanzilotto, Valeria
    Sapienza Univ Roma, Dept Chem, I-00185 Rome, Italy..
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden.;Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, F-75005 Paris, France..
    Beranova, Klara
    Elettra Sincrotrone Trieste SCPA, I-34149 Trieste, Italy.;Czech Acad Sci, FZU Inst Phys, Prague 18221, Czech Republic..
    Coreno, Marcello
    Ist Struttura, ISM, CNR, I-85050 Tito, Pz, Italy..
    de Simone, Monica
    Sincrotrone Trieste, IOM CNR, Lab TASC, I-34149 Trieste, Italy..
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    m-MTDATA on Au(111): Spectroscopic Evidence of Molecule-Substrate Interactions2022In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 126, no 6, p. 3202-3210Article in journal (Refereed)
    Abstract [en]

    The starburst pi-conjugated molecule based on triphenylamine (TPA) building blocks, 4,4',4 ''-tris(N-3-ethylphenyl-N-phenylamino)triphenylamine (C57H48N4, m-MTDATA), is widely used in optoelectronic devices due to its electron-donating properties. The electronic structure of m-MTDATA adsorbed on an Au(111) surface was investigated by means of photoelectron spectroscopy (PES) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. The results were further compared to gas-hase measurements and DFT calculations. Our results clearly indicate a significant molecule-substrate interaction that induces considerable modifications on the electronic structure of the adsorbate compared to the isolated molecule. The energy level alignment analysis shows that the HOMO-LUMO gap is filled by new interface states.

  • 43.
    Zhang, Teng
    et al.
    Beijing Inst Technol BIT, MIIT Key Lab Low Dimens Quantum Structure & Devi, Sch Integrated Circuits & Elect, Beijing 100081, Peoples R China..
    Grazioli, Cesare
    IOM CNR, Ist Officina Mat, Basovizza SS-14,Km 163-5, I-34149 Trieste, Italy..
    Yang, Huixia
    Beijing Inst Technol BIT, MIIT Key Lab Low Dimens Quantum Structure & Devi, Sch Integrated Circuits & Elect, Beijing 100081, Peoples R China..
    Jiang, Kaiyue
    Shanghai Jiao Tong Univ, Sch Chem & Chem Engn, Frontiers Sci Ctr Transformat Mol,Shanghai Lab El, State Key Lab Met Matrix Composites,Meso Entropy, Shanghai 200240, Peoples R China..
    Brumboiu, Iulia Emilia
    Pohang Univ Sci & Technol POSTECH, Dept Chem, Pohang 37673, South Korea..
    Jia, Liangguang
    Beijing Inst Technol BIT, MIIT Key Lab Low Dimens Quantum Structure & Devi, Sch Integrated Circuits & Elect, Beijing 100081, Peoples R China..
    Liu, Liwei
    Beijing Inst Technol BIT, MIIT Key Lab Low Dimens Quantum Structure & Devi, Sch Integrated Circuits & Elect, Beijing 100081, Peoples R China..
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Zhuang, Xiaodong
    Shanghai Jiao Tong Univ, Sch Chem & Chem Engn, Frontiers Sci Ctr Transformat Mol,Shanghai Lab El, State Key Lab Met Matrix Composites,Meso Entropy, Shanghai 200240, Peoples R China..
    Wang, Yeliang
    Beijing Inst Technol BIT, MIIT Key Lab Low Dimens Quantum Structure & Devi, Sch Integrated Circuits & Elect, Beijing 100081, Peoples R China..
    Spectroscopic Evidence of New Low-Dimensional Planar Carbon Allotropes Based on Biphenylene via On-Surface Ullmann Coupling2021In: CHEMISTRY-SWITZERLAND, ISSN 2624-8549, Vol. 3, no 3, p. 1057-1062Article in journal (Refereed)
    Abstract [en]

    The bottom-up synthesis and preliminary characterizations of a new biphenylene-based 2D framework are presented. This new low-dimensional carbon allotrope potentially completes the many hypothesized carbon networks based on biphenylene.

    Download full text (pdf)
    FULLTEXT01
  • 44.
    Zhang, Teng
    et al.
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Svensson, Pamela
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Brumboiu, Iulia Emilia
    Pohang Univ Sci & Technol POSTECH, Dept Chem, Pohang 37673, South Korea..
    Lanzilotto, Valeria
    Sapienza Univ Roma, Dept Chem, I-00185 Rome, Italy..
    Grazioli, Cesare
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Guarnaccio, Ambra
    ISM CNR, Ist Struttura Mat, I-85050 Tito, Pz, Italy..
    Johansson, Fredrik O.L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden.;Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, F-75005 Paris, France..
    Beranova, Klara
    Elettra Sincrotrone Trieste SCpA, I-34149 Trieste, Italy.;Czech Acad Sci, FZU Inst Phys, Prague 18221, Czech Republic..
    Coreno, Marcello
    ISM CNR, Ist Struttura Mat, I-85050 Tito, Pz, Italy..
    de Simone, Monica
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Floreano, Luca
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Cossaro, Albano
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy.;Univ Trieste, Dept Chem & Pharmaceut Sci, I-34127 Trieste, Italy..
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Clarifying the Adsorption of Triphenylamine on Au(111): Filling the HOMO-LUMO Gap2022In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 126, no 3, p. 1635-1643Article in journal (Refereed)
    Abstract [en]

    In this article, we analyze the electronic structure modifications of triphenylamine (TPA), a well-known electron donor molecule widely used in photovoltaics and optoelectronics, upon deposition on Au(111) at a monolayer coverage. A detailed study was carried out by synchrotron radiation-based photoelectron spectroscopy, near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, scanning tunneling microscopy (STM), and ab initio calculations. We detect a new feature in the pre-edge energy region of the N K-edge NEXAFS spectrum that extends over 3 eV, which we assign to transitions involving new electronic states. According to our calculations, upon adsorption, a number of new unoccupied electronic states fill the energy region between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the free TPA molecule and give rise to the new feature the pre-edge region of the NEXAFS spectrum. This finding highlights the occurrence of a considerable modification of the electronic structure of TPA. The appearance of new states in the HOMO-LUMO gap of TPA when adsorbed on Au(111) has crucial implications for the design of molecular nanoelectronic devices based on similar donor systems.

    Download full text (pdf)
    FULLTEXT01
  • 45.
    Zhang, Teng
    et al.
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Wang, Tingting
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Grazioli, Cesare
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Guarnaccio, Ambra
    ISM CNR, Ist Struttura Mat, I-85050 Tito, Pz, Italy.;ISM CNR, Ist Struttura Mat, I-34149 Trieste, Ts, Italy..
    Brumboiu, Iulia Emilia
    Pohang Univ Sci & Technol POSTECH, Dept Chem, Pohang 37673, South Korea..
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials. KTH Royal Inst Technol, Dept Chem, Div Appl Phys Chem, S-10044 Stockholm, Sweden.;Sorbonne Univ, Inst Nanosci Paris, UMR CNRS 7588, F-75005 Paris, France..
    Beranova, Klara
    Elettra Sincrotrone Trieste SCpA, Str Statale 14,Km 163-5, I-34149 Trieste, Italy.;Czech Acad Sci, FZU Inst Phys, Prague 18221, Czech Republic..
    Coreno, Marcello
    ISM CNR, Ist Struttura Mat, I-85050 Tito, Pz, Italy.;ISM CNR, Ist Struttura Mat, I-34149 Trieste, Ts, Italy..
    de Simone, Monica
    IOM CNR, Lab TASC, Sincrotrone Trieste, I-34149 Trieste, Italy..
    Brena, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Liu, Liwei
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Wang, Yeliang
    Beijing Inst Technol, Sch Integrated Circuits & Elect, MIIT Key Lab Low Dimens Quantum Struct & Devices, Beijing 100081, Peoples R China..
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Evidence of hybridization states at the donor/acceptor interface: case of m-MTDATA/PPT2022In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 34, no 21, article id 214008Article in journal (Refereed)
    Abstract [en]

    We performed a spectroscopic study on the m-MTDATA (donor) and PPT (acceptor) molecular vertical heterostructure. The electronic properties of the donor/acceptor interface have been comprehensively characterized by synchrotron radiation-based photoelectron spectroscopy and near-edge x-ray absorption fine structure. The spectroscopic results reveal the existence of new hybridization states in the original molecular energy gap, likely attributed to the interaction between the donor and the acceptor molecules at the interface. Such hybridized states can have a significant impact on the charge transport in organic electronic devices based on donor-acceptor molecules and can explain the increased efficiency of device using such molecules.

  • 46.
    Åhlund, John
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Schnadt, Joachim
    Nilson, Katharina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Göthelid, Emmanuelle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Schiessling, Joachim
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Besenbacher, Flemming
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Puglia, Carla
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    The adsorption of iron phthalocyanine on graphite: A scanning tunnelling microscopy study2007In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 601, no 17, p. 3661-3667Article in journal (Refereed)
    Abstract [en]

    Different adsorption phases of iron phthalocyanine (FePc) on highly oriented pyrolitic graphite (HOPG) have been characterized by scanning tunnelling microscopy (STM). Evaporation of FePc onto the graphite (0 0 0 1) surface, kept at room temperature, results in the formation of three-dimensional molecular islands.

    After annealing to 400 °C different two-dimensional features are identified, depending on the initial coverage. At low doses, domains with well defined boundaries have been observed, within which molecules tend to organise in chains. At higher coverage, islands exhibiting well-ordered densely-packed square or hexagonal molecular arrangement have been resolved. For the adsorption structures corresponding to one monolayer islands our results show that the molecules adsorb with the molecular plane parallel to the surface. The high resolution STM images allow us to resolve the orientation of single molecules and subsequently we suggest that the molecular monolayer is stabilized by van der Waals interactions. The characterization of the observed Moiré contrast and a comparison with other similar systems underlines the importance of the central metal in the molecule–molecule and molecule–substrate interactions, which govern the molecular adsorption geometry.

1 - 46 of 46
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