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Simonov, Konstantin
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Publications (10 of 18) Show all publications
Marks, K., Yazdi, M. G., Piskorz, W., Simonov, K., Stefanuik, R., Sostina, D., . . . Ostrom, H. (2019). Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111). Journal of Chemical Physics, 150(24), Article ID 244704.
Open this publication in new window or tab >>Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111)
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2019 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 24, article id 244704Article in journal (Refereed) Published
Abstract [en]

The temperature dependent dehydrogenation of naphthalene on Ni(111) has been investigated using vibrational sum-frequency generation spectroscopy, X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory with the aim of discerning the reaction mechanism and the intermediates on the surface. At 110 K, multiple layers of naphthalene adsorb on Ni(111); the first layer is a flat lying chemisorbed monolayer, whereas the next layer(s) consist of physisorbed naphthalene. The aromaticity of the carbon rings in the first layer is reduced due to bonding to the surface Ni-atoms. Heating at 200 K causes desorption of the multilayers. At 360 K, the chemisorbed naphthalene monolayer starts dehydrogenating and the geometry of the molecules changes as the dehydrogenated carbon atoms coordinate to the nickel surface; thus, the molecule tilts with respect to the surface, recovering some of its original aromaticity. This effect peaks at 400 K and coincides with hydrogen desorption. Increasing the temperature leads to further dehydrogenation and production of H-2 gas, as well as the formation of carbidic and graphitic surface carbon. Published under license by AIP Publishing.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-390812 (URN)10.1063/1.5098533 (DOI)000473303200040 ()31255092 (PubMedID)
Funder
Swedish Research Council, 2015-05242Swedish Foundation for Strategic Research Swedish Energy Agency, 34721-2
Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
Jacobse, P. H., Simonov, K. A., Mangnus, M. J. J., Svirskiy, G. I., Generalov, A. V., Vinogradov, A. S., . . . Swart, I. (2019). One Precursor but Two Types of Graphene Nanoribbons: On-Surface Transformations of 10,10'-Dichloro-9,9'-bianthryl on Ag(111). The Journal of Physical Chemistry C, 123(14), 8892-8901
Open this publication in new window or tab >>One Precursor but Two Types of Graphene Nanoribbons: On-Surface Transformations of 10,10'-Dichloro-9,9'-bianthryl on Ag(111)
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2019 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 14, p. 8892-8901Article in journal (Refereed) Published
Abstract [en]

On-surface synthesis has emerged in the last decade as a method to create graphene nanoribbons (GNRs) with atomic precision. The underlying premise of this bottom-up strategy is that precursor molecules undergo a well-defined sequence of inter- and intramolecular reactions, leading to the formation of a single product. As such, the structure of the GNR is encoded in the precursors. However, recent examples have shown that not only the molecule, but also the coinage metal surface on which the reaction takes place, plays a decisive role in dictating the nanoribbon structure. In this work, we use scanning probe microscopy and X-ray photoelectron spectroscopy to investigate the behavior of 10,10'-dichloro-9,9'-bianthryl (DCBA) on Ag(111). Our study shows that Ag(111) can induce the formation of both seven-atom wide armchair GNRs (7-acGNRs) and 3,1-chiral GNRs (3,1-cGNRs), demonstrating that a single molecule on a single surface can react to different nanoribbon products. We additionally show that coadsorbed dibromoperylene can promote surface-assisted dehydrogenative coupling in DCBA, leading to the exclusive formation of 3,1-cGNRs.

National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-382854 (URN)10.1021/acs.jpcc.8b12209 (DOI)000464768600048 ()31001369 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyEU, FP7, Seventh Framework Programme, 321319Knut and Alice Wallenberg FoundationCarl Tryggers foundation
Available from: 2019-05-15 Created: 2019-05-15 Last updated: 2019-05-15Bibliographically approved
Svirskiy, G. I., Generalov, A. V., Klyushin, A. Y., Simonov, K., Krasnikov, S. A., Vinogradov, N. A., . . . Vinogradov, A. S. (2018). Comparative X-Ray Absorption Analysis of the Spectrum of Vacant Electronic States in Cobalt and Nickel Tetraphenylporphyrin Complexes. Physics of the solid state, 60(3), 581-591
Open this publication in new window or tab >>Comparative X-Ray Absorption Analysis of the Spectrum of Vacant Electronic States in Cobalt and Nickel Tetraphenylporphyrin Complexes
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2018 (English)In: Physics of the solid state, ISSN 1063-7834, E-ISSN 1090-6460, Vol. 60, no 3, p. 581-591Article in journal (Refereed) Published
Abstract [en]

The energy distributions and the properties of the lower vacant electronic states in cobalt and nickel tetraphenylporphyrin complexes CoTPP and NiTPP are studied by X-ray absorption spectroscopy. Quasimolecular analysis of the experimental absorption spectra measured in the region of the 2p and 1s ionization thresholds of complexing metal atoms, as well as the 1s thresholds of ligand atoms (nitrogen and carbon), is based on the comparison of the corresponding spectra with each other and with the spectra of the simplest nickel porphyrin NiP. It has been established that, despite a general similarity of the spectra of nitrogen and carbon in CoTPP and NiTPP, the fine structure of the 2p and 1s absorption spectra of cobalt and nickel atoms are radically different. The observed differences in the spectra of cobalt and nickel are associated with the features of the energy distribution of vacant 3d electron states. The presence in CoTPP of the partially filled valence 3db2g molecular orbital (MO) results in the appearance in the cobalt spectra of a low-energy band, which is absent in the spectrum of nickel in NiTPP and leads to a doublet structure of transitions to b1g and e g MOs due to the exchange interaction between 3d electrons in partially filled 3db2g and 3db1g or 3de g MOs. The spectrum of vacant states in CoTPP differs from that in NiTPP also due to the smaller energy distance between 3db1g and e g MOs and the different positions of nonbonding MOs with the C2p character of the porphine ligand.

National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-350880 (URN)10.1134/S1063783418030307 (DOI)000427598800027 ()
Available from: 2018-05-23 Created: 2018-05-23 Last updated: 2018-05-25Bibliographically approved
Lanzilotto, V., Silva, J. L., Zhang, T., Stredansky, M., Grazioli, C., Simonov, K., . . . Puglia, C. (2018). Spectroscopic Fingerprints of Intermolecular H-Bonding Interactions in Carbon Nitride Model Compounds. Chemistry - A European Journal, 24(53), 14198-14206
Open this publication in new window or tab >>Spectroscopic Fingerprints of Intermolecular H-Bonding Interactions in Carbon Nitride Model Compounds
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2018 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 24, no 53, p. 14198-14206Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
WILEY-V C H VERLAG GMBH, 2018
Keywords
density functional calculations, hydrogen bonds, carbon nitrides, photoelectron spectroscopy, X-ray absorption spectroscopy
National Category
Theoretical Chemistry
Identifiers
urn:nbn:se:uu:diva-366732 (URN)10.1002/chem.201802435 (DOI)000445177600028 ()30009392 (PubMedID)
Funder
Carl Tryggers foundation
Available from: 2018-12-11 Created: 2018-12-11 Last updated: 2018-12-11Bibliographically approved
Simonov, K., Generalov, A. V., Vinogradov, A. S., Svirskiy, G. I., Cafolla, A. A., McGuinness, C., . . . Preobrajenski, A. B. (2018). Synthesis of armchair graphene nanoribbons from the 10,10 '-dibromo-9,9 '-bianthracene molecules on Ag(111): the role of organometallic intermediates. Scientific Reports, 8, Article ID 3506.
Open this publication in new window or tab >>Synthesis of armchair graphene nanoribbons from the 10,10 '-dibromo-9,9 '-bianthracene molecules on Ag(111): the role of organometallic intermediates
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 3506Article in journal (Refereed) Published
Abstract [en]

We investigate the bottom-up growth of N = 7 armchair graphene nanoribbons (7-AGNRs) from the 10,10'-dibromo-9,9'-bianthracene (DBBA) molecules on Ag(111) with the focus on the role of the organometallic (OM) intermediates. It is demonstrated that DBBA molecules on Ag(111) are partially debrominated at room temperature and lose all bromine atoms at elevated temperatures. Similar to DBBA on Cu(111), debrominated molecules form OM chains on Ag(111). Nevertheless, in contrast with the Cu(111) substrate, formation of polyanthracene chains from OM intermediates via an Ullmann-type reaction is feasible on Ag(111). Cleavage of C-Ag bonds occurs before the thermal threshold for the surface-catalyzed activation of C-H bonds on Ag(111) is reached, while on Cu(111) activation of C-H bonds occurs in parallel with the cleavage of the stronger C-Cu bonds. Consequently, while OM intermediates obstruct the Ullmann reaction between DBBA molecules on the Cu(111) substrate, they are required for the formation of polyanthracene chains on Ag(111). If the Ullmann-type reaction on Ag(111) is inhibited, heating of the OM chains produces nanographenes instead. Heating of the polyanthracene chains produces 7-AGNRs, while heating of nanographenes causes the formation of the disordered structures with the possible admixture of short GNRs.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2018
National Category
Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-349343 (URN)10.1038/s41598-018-21704-3 (DOI)000425728600062 ()29472611 (PubMedID)
Funder
Swedish Research CouncilSwedish Energy AgencyEU, FP7, Seventh Framework Programme, 321319Knut and Alice Wallenberg Foundation
Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-04-26Bibliographically approved
Senkovskiy, B. V., Fedorov, A. V., Haberer, D., Farjam, M., Simonov, K. A., Preobrajenski, A. B., . . . Grueneis, A. (2017). Semiconductor-to-Metal Transition and Quasiparticle Renormalization in Doped Graphene Nanoribbons. ADVANCED ELECTRONIC MATERIALS, 3(4), Article ID 1600490.
Open this publication in new window or tab >>Semiconductor-to-Metal Transition and Quasiparticle Renormalization in Doped Graphene Nanoribbons
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2017 (English)In: ADVANCED ELECTRONIC MATERIALS, ISSN 2199-160X, Vol. 3, no 4, article id 1600490Article in journal (Refereed) Published
Abstract [en]

A semiconductor-to-metal transition in N = 7 armchair graphene nanoribbons causes drastic changes in its electron and phonon system. By using angle-resolved photoemission spectroscopy of lithium-doped graphene nanoribbons, a quasiparticle band gap renormalization from 2.4 to 2.1 eV is observed. Reaching high doping levels (0.05 electrons per atom), it is found that the effective mass of the conduction band carriers increases to a value equal to the free electron mass. This giant increase in the effective mass by doping is a means to enhance the density of states at the Fermi level which can have palpable impact on the transport and optical properties. Electron doping also reduces the Raman intensity by one order of magnitude, and results in relatively small (4 cm(-1)) hardening of the G phonon and softening of the D phonon. This suggests the importance of both lattice expansion and dynamic effects. The present work highlights that doping of a semiconducting 1D system is strikingly different from its 2D or 3D counterparts and introduces doped graphene nanoribbons as a new tunable quantum material with high potential for basic research and applications.

Place, publisher, year, edition, pages
WILEY, 2017
National Category
Materials Engineering
Identifiers
urn:nbn:se:uu:diva-322215 (URN)10.1002/aelm.201600490 (DOI)000399448600005 ()
Funder
EU, European Research Council, 648589 321319German Research Foundation (DFG), CRC1238 A1 GR 3708/2-1Swedish Research Council
Available from: 2017-05-17 Created: 2017-05-17 Last updated: 2017-05-22Bibliographically approved
Simonov, K. A., Vinogradov, N. A., Vinogradov, A. S., Generalov, A. V., Svirskiy, G. I., Cafolla, A. A., . . . Preobrajenski, A. B. (2016). Effect of Electron Injection in Copper-Contacted Graphene Nanoribbons. Nano Reseach, 9(9), 2735-2746
Open this publication in new window or tab >>Effect of Electron Injection in Copper-Contacted Graphene Nanoribbons
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2016 (English)In: Nano Reseach, ISSN 1998-0124, E-ISSN 1998-0000, Vol. 9, no 9, p. 2735-2746Article in journal (Refereed) Published
Abstract [en]

For practical electronic device applications of graphene nanoribbons (GNRs), it is essential to have abrupt and well-defined contacts between the ribbon and the adjacent metal lead. By analogy with graphene, these contacts can induce electron or hole doping, which may significantly affect the I/V characteristics of the device. Cu is among the most popular metals of choice for contact materials. In this study, we investigate the effect of in situ intercalation of Cu on the electronic structure of atomically precise, spatially aligned armchair GNRs of width N = 7 (7-AGNRs) fabricated via a bottom-up method on the Au(788) surface. Scanning tunneling microscopy data reveal that the complete intercalation of about one monolayer of Cu under 7-AGNRs can be facilitated by gentle annealing of the sample at 80 A degrees C. Angle-resolved photoemission spectroscopy (ARPES) data clearly reflect the one-dimensional character of the 7-AGNR band dispersion before and after intercalation. Moreover, ARPES and core-level photoemission results show that intercalation of Cu leads to significant electron injection into the nanoribbons, which causes a pronounced downshift of the valence and conduction bands of the GNR with respect to the Fermi energy (Delta E similar to 0.5 eV). As demonstrated by ARPES and X-ray absorption spectroscopy measurements, the effect of Cu intercalation is restricted to n-doping only, without considerable modification of the band structure of the GNRs. Post-annealing of the 7-AGNRs/Cu/Au(788) system at 200 A degrees C activates the diffusion of Cu into Au and the formation of a Cu-rich surface Au layer. Alloying of intercalated Cu leads to the recovery of the initial position of GNR-related bands with respect to the Fermi energy (E (F)), thus, proving the tunability of the induced n-doping.

Keywords
graphene nanoribbons, bottom-up method, copper intercalation, charge injection, ARPES, Scanning tunneling microscopy
National Category
Condensed Matter Physics Atom and Molecular Physics and Optics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-295867 (URN)10.1007/s12274-016-1162-2 (DOI)000382882200023 ()
Funder
Swedish Energy AgencySwedish Research CouncilEU, European Research Council, 321319Knut and Alice Wallenberg Foundation
Available from: 2016-06-10 Created: 2016-06-10 Last updated: 2017-11-28Bibliographically approved
Simonov, K. (2016). Effect of Substrate on Bottom-Up Fabrication and Electronic Properties of Graphene Nanoribbons. (Doctoral dissertation). Uppsala: Acta Universitatis Upsaliensis
Open this publication in new window or tab >>Effect of Substrate on Bottom-Up Fabrication and Electronic Properties of Graphene Nanoribbons
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Taking into account the technological demand for the controlled preparation of atomically precise graphene nanoribbons (GNRs) with well-defined properties, the present thesis is focused on the investigation of the role of the underlying metal substrate in the process of building GNRs using bottom-up strategy and on the changes in the electronic structure of GNRs induced by the GNR-metal interaction. The combination of surface sensitive synchrotron-radiation-based spectroscopic techniques and scanning tunneling microscopy with in situ sample preparation allowed to trace evolution of the structural and electronic properties of the investigated systems.

Significant impact of the substrate activity on the growth dynamics of armchair GNRs of width N = 7 (7-AGNRs) prepared on inert Au(111) and active Cu(111) was demonstrated. It was shown that unlike inert Au(111) substrate, the mechanism of GNRs formation on Ag(111) and Cu(111) includes the formation of organometallic intermediates based on the carbon-metal-carbon bonds. Experiments performed on Cu(111) and Cu(110), showed that a change of the balance between molecular diffusion and intermolecular interaction significantly affects the on-surface reaction mechanism making it impossible to grow GNRs on Cu(110).

It was demonstrated that deposition of metals on spatially aligned GNRs prepared on stepped Au(788) substrate allows to investigate GNR-metal interaction using angle-resolved photoelectron spectroscopy. In particular intercalation of one monolayer of copper beneath 7-AGNRs leads to significant electron injection into the nanoribbons, indicating that charge doping by metal contacts must be taken into account when designing GNR/electrode systems. Alloying of intercalated copper with gold substrate upon post-annealing at 200°C leads to a recovery of the initial position of GNR-related bands with respect to the Fermi level, thus proving tunability of the induced n-doping. Contrary, changes in the electronic structure of 7-AGNRs induced by the deposition of Li are not reversible.  It is demonstrated that via lithium doping 7-AGNRs can be transformed from a semiconductor into a metal state due to the partial filling of the conduction band. The band gap of Li-doped GNRs is reduced and the effective mass of the conduction band carriers is increased.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. p. 101
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1385
Keywords
graphene nanoribbons, bottom-up, substrate, metal contact, electronic structure, electron doping, PES, ARPES, NEXAFS, STM
National Category
Atom and Molecular Physics and Optics Condensed Matter Physics Other Physics Topics
Research subject
Physics with spec. in Atomic, Molecular and Condensed Matter Physics
Identifiers
urn:nbn:se:uu:diva-295884 (URN)978-91-554-9610-4 (ISBN)
External cooperation:
Public defence
2016-09-23, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2016-08-16 Created: 2016-06-10 Last updated: 2016-08-25
Simonov, K. A., Vinogradov, N. A., Vinogradov, A. S., Generalov, A. V., Zagrebina, E. M., Mårtensson, N., . . . Preobrajenski, A. B. (2015). Comment on "Bottom-Up Graphene-Nanoribbon Fabrication Reveals Chiral Edges and Enantioselectivity" [Letter to the editor]. ACS Nano, 9(4), 3399-3403
Open this publication in new window or tab >>Comment on "Bottom-Up Graphene-Nanoribbon Fabrication Reveals Chiral Edges and Enantioselectivity"
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2015 (English)In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 9, no 4, p. 3399-3403Article in journal, Letter (Refereed) Published
National Category
Condensed Matter Physics Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-257309 (URN)10.1021/nn506439a (DOI)000353867000002 ()25916424 (PubMedID)
Available from: 2015-07-02 Created: 2015-07-01 Last updated: 2017-12-04
Zagrebina, E. M., Generalov, A. V., Klyushin, A. Y., Simonov, K. A., Vinogradov, N. A., Dubois, M., . . . Vinogradov, A. S. (2015). Comparative NEXAFS, NMR, and FTIR Study of Various-Sized Nanodiamonds: As-Prepared and Fluorinated. The Journal of Physical Chemistry C, 119(1), 835-844
Open this publication in new window or tab >>Comparative NEXAFS, NMR, and FTIR Study of Various-Sized Nanodiamonds: As-Prepared and Fluorinated
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2015 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 1, p. 835-844Article in journal (Refereed) Published
National Category
Other Physics Topics
Identifiers
urn:nbn:se:uu:diva-246371 (URN)10.1021/jp510618s (DOI)000347744700091 ()
Available from: 2015-03-05 Created: 2015-03-05 Last updated: 2017-12-04Bibliographically approved
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