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  • 1.
    Abid, Abdul Rahman
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland..
    Pelimanni, Eetu
    Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland..
    Reinhardt, Maximilian
    Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland..
    Boudjemia, Nacer
    Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland..
    Kivimaki, Antti
    Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland.;Lund Univ, Max Lab 4, Lund, Sweden..
    Huttula, Marko
    Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland..
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Patanen, Minna
    Univ Oulu, Nano & Mol Syst Res Unit, Oulu, Finland..
    Electron-ion coincidence spectroscopy of a large organic molecule: photofragmentation of avobenzone after valence and core ionisation2020In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 53, no 24, article id 244001Article in journal (Refereed)
    Abstract [en]

    The Avobenzone (AVOB) molecule is very photoactive and undergoes irreversible degradation upon irradiation. We studied its valence and core-level (C1s and O1s) photoionisation and subsequent photofragmentation with photoelectron spectroscopy and photoelectron-photoion-photoion coincidence (PEPIPICO) spectroscopy. AVOB is one of the largest molecules studied with this technique. The results show that the AVOB molecule dissociates into an extensive range of fragments by different pathways with little element or site-selectivity. The coincident maps were used to determine selected fragment separation sequences by analysing the slopes of patterns from ion pairs after the core ionisation. Charge delocalisation over the benzene rings and their relative stability favor fragmentation by cleavage of the bridge between them.

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  • 2.
    Abid, Abdul Rahman
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Univ Oulu, Nano & Mol Syst Res Unit, Fac Sci, POB 3000, Oulu 90570, Finland.
    Reinhardt, Maximilian
    Boudjemia, Nacer
    Pelimanni, Eetu
    Milosavljevic, Aleksandar R.
    Saak, Clara-Magdalena
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Huttula, Marko
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Patanen, Minna
    The effect of relative humidity on CaCl2 nanoparticles studied by soft X-ray absorption spectroscopy2021In: RSC Advances, E-ISSN 2046-2069, Vol. 11, no 4, p. 2103-2111Article in journal (Refereed)
    Abstract [en]

    Ca- and Cl-containing nanoparticles are common in atmosphere, originating for example from desert dust and sea water. The properties and effects on atmospheric processes of these aerosol particles depend onthe relative humidity (RH) as they are often both hygroscopic and deliquescent. We present here a study of surface structure of free-flying CaCl2 nanoparticles (CaCl2-NPs) in the 100 nm size regime prepared at different humidity levels (RH: 11–85%). We also created mixed nanoparticles by aerosolizing a solution ofCaCl2 and phenylalanine (Phe), which is a hydrophobic amino acid present in atmosphere. Information of hydration state of CaCl2-NPs and production of mixed CaCl2 + Phe nanoparticles was obtained using soft X-ray absorption spectroscopy (XAS) at Ca 2p, Cl 2p, C 1s, and O 1s edges. We also report Ca 2p andCl 2p X-ray absorption spectra of an aqueous CaCl2 solution. The O 1s X-ray absorption spectra measured from hydrated CaCl2-NPs resemble liquid-like water spectrum, which is heavily influenced by the presence of ions. Core level spectra of Ca2+ and Cl- ions do not show a clear dependence of % RH, indicating that the first coordination shell remains similar in all measured hydrated CaCl2-NPs, but they differ from aqueous solution and solid CaCl2.

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  • 3. Abu-samha, M
    et al.
    Borve, K. J.
    Winkler, M
    Harnes, J
    Saethre, L. J.
    Lindblad, A
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Bergersen, H
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Björneholm, O
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Svensson, S
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Öhrwall, G
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    The local structure of small water clusters: imprints on the core-level photoelectron spectrum2009In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 42, no 5, p. 055201-Article in journal (Refereed)
    Abstract [en]

    We report on an O 1s photoelectron-spectroscopy study of small neutral water clusters produced by adiabatic expansion. The photoelectron spectra were acquired under two different experimental conditions. At intermediate resolution, the cluster signal was characterized by a very broad O 1s peak with a flat top. In the second set of measurements, resolution was significantly increased at the cost of lower count rates. The cluster signal was now partly resolved into a bimodal structure. Extensive theoretical calculations were undertaken to facilitate an interpretation of the spectrum. These results suggest that the bimodal feature may be ascribed to ionization of water molecules in different hydrogen-bonding configurations, more specifically, molecules characterized by donation of either one or both hydrogen atoms in H-bonding.

  • 4. Abu.samha, M.
    et al.
    Börve, K. J.
    Saethre, L. J.
    Öhrwall, Gunnar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Bergersen, Henrik
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Rander, Torbjörn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Björneholm, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Tchaplyguine, Maxim
    Lineshapes in carbon 1s photoelectron spectra of methanol clusters2006In: Physical Chemistry Chemical Physics, Vol. 21, p. 2473-Article in journal (Refereed)
  • 5.
    Akiyama, Tomoko
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany.
    Grånäs, Oscar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Influence of Ionization on the Dynamics of HydrocarbonsManuscript (preprint) (Other academic)
    Abstract [en]

    The structural changes of four hydrocarbons induced by ionization was investigated using molecular dynamics simulations based on density functional theory within the Born-Oppenheimer approximation. Bond lengths, bond breaking and proton rearrangement was analysed for propane, propene, propyne and propadiene at charges ranging from 0 to +3.   Similar to the case of amino acids, the back-bone of linear hydrocarbons is stabilized by reducing theeffectiv elevel of ionization through dropping protons. Subsequent iniozations, up the the level of 3+, do not break thelinear carbon chain within 250 fs, however the bond-orderis reduced, and bond-distances approach that of a single-bond

  • 6.
    Andersson, T.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Zhang, C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Mikkela, M-H
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Jankala, K.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Anin, D.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Urpelainen, S.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Huttula, M.
    Oulu Univ, Dept Phys Sci, Box 3000, FI-90014 Oulu, Finland..
    Tchaplyguine, M.
    Lund Univ, Max Lab, Box 118, SE-22363 Lund, Sweden..
    Electronic structure transformation in small bare Au clusters as seen by x-ray photoelectron spectroscopy2017In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 50, no 1, article id 015102Article in journal (Refereed)
    Abstract [en]

    Free bare gold clusters in the size range from few tens to few hundred atoms (<= 1 nm dimensions) have been produced in a beam, and the size-dependent development of their full valence band including the 5d and 6s parts has been mapped 'on the fly' by synchrotron-based photoelectron spectroscopy. The Au 4f core level has been also probed, and the cluster-specific Au 4f ionization energies have been used to estimate the cluster size. The recorded in the present work valence spectra of the small clusters are compared with the spectra of the large clusters (N similar to 10(3)) created by us using a magnetron-based gas aggregation source. The comparison shows a substantially narrower 5d valence band and the decrease in its splitting for gold clusters in the size range of few hundred atoms and below. Our DFT calculations involving the pseudopotential method show that the 5d band width of the ground state increases with the cluster size and by the size N = 20 becomes comparable with the experimental width of the valence photoelectron spectrum. Similar to the earlier observations on supported clusters we interpret our experimental and theoretical results as due to the undercoordination of a large fraction of atoms in the clusters with N similar to 10(2) and below. The consequences of such electronic structure of small gold clusters are discussed in connection with their specific physical and chemical properties related to nanoplasmonics and nanocatalysis.

  • 7.
    Andersson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Zhang, Chaofan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Mikkelä, M. -H
    Anin, Dmitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Jänkälä, K.
    Tchaplyguine, M.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Huttula, M.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Photon energy influence on valence photoelectron spectra of silver clusters2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 388, no 15, p. 152028-Article in journal (Refereed)
    Abstract [en]

    Silver clusters in the size range of ∼102 constituent atoms have been studied using photoelectron spec-troscopy. The 5s and 4d valence bands have been probed with 40 and 60.5 eV photon energies. Differences in the valence band spectral features have been observed and are discussed in view of earlier results on copper clusters and in terms of differences in mean free path for electrons of different energies.

  • 8.
    Andersson, Tomas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Zhang, Chaofan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Tchaplyguine, Maxim
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Mårtensson, Nils
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    The electronic structure of free aluminum clusters: Metallicity and plasmons2012In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 136, no 20, p. 204504-Article in journal (Refereed)
    Abstract [en]

    The electronic structure of free aluminum clusters with similar to 3-4 nm radius has been investigated using synchrotron radiation-based photoelectron and Auger electron spectroscopy. A beam of free clusters has been produced using a gas-aggregation source. The 2p core level and the valence band have been probed. Photoelectron energy-loss features corresponding to both bulk and surface plasmon excitation following photoionization of the 2p level have been observed, and the excitation energies have been derived. In contrast to some expectations, the loss features have been detected at energies very close to those of the macroscopic solid. The results are discussed from the point of view of metallic properties in nanoparticles with a finite number of constituent atoms.

  • 9. Baev, A.
    et al.
    Salek, P.
    Gel'mukhanov, F. Kh.
    Ågren, H.
    Naves de Brito, A.
    Björneholm, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
    Svensson, Svante
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
    Picturing molecular femtosecond processes through an ultra-fast controllable X-ray shutter2003In: Chemical Physics, Vol. 289, p. 51-56Article in journal (Refereed)
  • 10. Barth, S.
    et al.
    Joshi, S.
    Marburger, S.
    Ulrich, V.
    Lindblad, Andreas
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Öhrwall, Gunnar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Björneholm, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Hergenhahn, U.
    Observation of resonant interatomic coulombic decay in Ne clusters2005In: J. Chem. Phys., Vol. 122, p. 241102-Article in journal (Refereed)
  • 11.
    Bergersen, Henrik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Abu-samba, M.
    Harnes, J.
    Björneholm, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Svensson, Svante
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Saethre, L. J.
    Börve, K. J.
    Size of neutral argon clusters from core-level photoelectron spectroscopy2006In: Physical Chemistry Chemical Physics, Vol. 16, p. 1891-Article in journal (Refereed)
  • 12.
    Bergersen, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Abu-samha, M.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Marinho, Ricardo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Tchaplyguine, M.
    Børve, K. J.
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Two size regimes of methanol clusters produced by adiabatic expansion2006In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 125, no 18, p. 184303-Article in journal (Refereed)
    Abstract [en]

    Free neutral methanol clusters produced by adiabatic expansion have been studied by photoelectron spectroscopy and line shape modeling. The results show that clusters belonging to two distinct size regimes can be produced by changing the expansion conditions. While the larger size regime can be well described by line shapes calculated for clusters consisting of hundreds of molecules, the smaller size regime corresponds to methanol oligomers, predominantly of cyclic structure. There is little contribution from dimers to the spectra.

  • 13.
    Bergersen, Henrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Marinho, R. R. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Pokapanich, Wandared
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sæthre, L. J.
    Department of Chemistry, University of Bergen.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    Öhrwall, Gunnar
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V.
    A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide2007In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 19, no 32, p. 326101-Article in journal (Refereed)
    Abstract [en]

    Photoelectron spectra of tetrabutylammonium iodide (TBAI) dissolved in water have been recorded using a novel experimental set-up, which enables photoelectron spectroscopy of volatile liquids. The set-up is described in detail. Ionization energies are reported for I 5p, I 4d, C 1s and N 1s. The C 1s spectrum shows evidence of inelastic scattering of the photoelectrons, that differs from the case of TBAI in formamide.

  • 14.
    Björneholm, Olle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hansen, Martin H.
    Tech Univ Denmark, DK-2800 Lyngby, Denmark.;Univ Copenhagen, Dept Chem, Univ Pk 5, DK-2100 Copenhagen, Denmark..
    Hodgson, Andrew
    Univ Liverpool, Dept Chem, Liverpool L69 7ZD, Merseyside, England..
    Liu, Li-Min
    UCL, London Ctr Nanotechnol, Thomas Young Ctr, Dept Phys & Astron, London WC1E 6BT, England.;UCL, Dept Chem, London WC1E 6BT, England.;Beijing Computat Sci Res Ctr, Beijing 100193, Peoples R China..
    Limmer, David T.
    Princeton Univ, Princeton Ctr Theoret Sci, Princeton, NJ 08544 USA..
    Michaelides, Angelos
    UCL, London Ctr Nanotechnol, Thomas Young Ctr, Dept Phys & Astron, London WC1E 6BT, England.;UCL, Dept Chem, London WC1E 6BT, England..
    Pedevilla, Philipp
    UCL, London Ctr Nanotechnol, Thomas Young Ctr, Dept Phys & Astron, London WC1E 6BT, England.;UCL, Dept Chem, London WC1E 6BT, England..
    Rossmeisl, Jan
    Univ Copenhagen, Dept Chem, Univ Pk 5, DK-2100 Copenhagen, Denmark..
    Shen, Huaze
    Peking Univ, Int Ctr Quantum Mat, Beijing 100871, Peoples R China.;Peking Univ, Sch Phys, Beijing 100871, Peoples R China..
    Tocci, Gabriele
    UCL, London Ctr Nanotechnol, Thomas Young Ctr, Dept Phys & Astron, London WC1E 6BT, England.;UCL, Dept Chem, London WC1E 6BT, England.;Ecole Polytech Fed Lausanne, Sch Engn, Inst Bioengn & Mat Sci & Engn, Lab Fundamental BioPhoton,Lab Computat Sci & Mode, CH-1015 Lausanne, Switzerland.;Ecole Polytech Fed Lausanne, Lausanne Ctr Ultrafast Sci, CH-1015 Lausanne, Switzerland..
    Tyrode, Eric
    KTH Royal Inst Technol, Dept Chem, S-10044 Stockholm, Sweden..
    Walz, Marie-Madeleine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics.
    Werner, Josephina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics. Swedish Univ Agr Sci, Dept Chem & Biotechnol, Box 7015, S-75007 Uppsala, Sweden..
    Bluhm, Hendrik
    Lawrence Berkeley Natl Lab, Div Chem Sci, Berkeley, CA 94720 USA..
    Water at Interfaces2016In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 116, no 13, p. 7698-7726Article, review/survey (Refereed)
    Abstract [en]

    The interfaces of neat water and aqueous solutions play a prominent role in many technological processes and in the environment. Examples of aqueous interfaces are ultrathin water films that cover most hydrophilic surfaces under ambient relative humidities, the liquid/solid interface which drives many electrochemical reactions, and the liquid/vapor interface, which governs the uptake and release of trace gases by the oceans and cloud droplets. In this article we review some of the recent experimental and theoretical advances in our knowledge of the properties of aqueous interfaces and discuss open questions and gaps in our understanding.

  • 15.
    Björneholm, Olle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Muchova, Eva
    Univ Chem & Technol, Prague, Czech Republic..
    Hot spots of radiation damage from extensive water ionization around metal ions2023In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 15, no 10, p. 1338-1339Article in journal (Other academic)
    Abstract [en]

    Radiation damage in biological systems by radicals and low-energy electrons formed from water ionization is a consequence of ultrafast processes that follow core-level ionization of hydrated metal ions. More details of the complex pathway are now revealed from the study of aluminium-ion relaxation through sequential electron-transfer-mediated decay.

  • 16.
    Björneholm, Olle
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Werner, Josephina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Ottosson, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Öhrwall, Gunnar
    Ekholm, Victor
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Winter, Bernd
    Unger, Isaak
    Söderström, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Deeper Insight into Depth-Profiling of Aqueous Solutions Using Photoelectron Spectroscopy2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 50, p. 29333-29339Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) is widely used to probe properties such as molecular stoichiometry, microscopic distributions relative to the surface by so-called "depth-profiling", and molecular orientation. Such studies usually rely on the core-level photoionization cross sections being independent of molecular composition. The validity of this assumption has recently been questioned, as a number of gas-phase molecules have been shown to exhibit photon-energy-dependent nonstochiometric intensity oscillations arising from EXAFS-like modulations of the photoionization cross section. We have studied this phenomenon in trichloroethanol in both gas phase and dissolved in water. The gas-phase species exhibits pronounced intensity oscillations, similar to the ones observed for other gas-phase molecules. These oscillations are also observed for the dissolved species, implying that the effect has to be taken into account when performing depth-profiling experiments of solutions and other condensed matter systems. The similarity between the intensity oscillations for gas phase and dissolved species allows us to determine the photoelectron kinetic energy of maximum surface sensitivity, ~100 eV, which lies in the range of pronounced intensity oscillations.

  • 17.
    Blanco, Yina Salamanca
    et al.
    Swedish Univ Agr Sci, Dept Mol Sci, POB 7015, SE-75007 Uppsala, Sweden;Univ El Bosque, Environm Engn Program, Carrera 7b Bis 132-11, Bogota, Colombia;Univ El Bosque, Chem Dept, Carrera 7b Bis 132-11, Bogota, Colombia.
    Topel, Onder
    Swedish Univ Agr Sci, Dept Mol Sci, POB 7015, SE-75007 Uppsala, Sweden;Akdeniz Univ, Dept Chem, Fac Sci, TR-07058 Antalya, Turkey.
    Bajnoczi, Eva G.
    Swedish Univ Agr Sci, Dept Mol Sci, POB 7015, SE-75007 Uppsala, Sweden.
    Werner, Josephina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Swedish Univ Agr Sci, Dept Mol Sci, POB 7015, SE-75007 Uppsala, Sweden.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Persson, Ingmar
    Swedish Univ Agr Sci, Dept Mol Sci, POB 7015, SE-75007 Uppsala, Sweden.
    Chemical equilibria of aqueous ammonium-carboxylate systems in aqueous bulk, close to and at the water-air interface2019In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 21, no 23, p. 12434-12445Article in journal (Refereed)
    Abstract [en]

    Previous studies have shown that the water-air interface and a number of water molecule layers just below it, the surface region, have significantly different physico-chemical properties, such as lower relative permittivity and density, than bulk water. The properties in the surface region of water favor weakly hydrated species as neutral molecules, while ions requiring strong hydration and shielding of their charge are disfavored. In this study the equilibria NH4+(aq) + RCOO-(aq) reversible arrow NH3(aq) + RCOOH(aq) are investigated for R = CnH2n+1, n = 0-8, as open systems, where ammonia and small carboxylic acids in the gas phase above the water surface are removed from the system by a gentle controlled flow of nitrogen to mimic the transport of volatile compounds from water droplets into air. It is shown that this non-equilibrium transport of chemicals can be sufficiently large to cause a change of the chemical content of the aqueous bulk. Furthermore, X-ray photoelectron spectroscopy (XPS) has been used to determine the relative concentration of alkyl carboxylic acids and their conjugated alkyl carboxylates in aqueous surfaces using a micro-jet. These studies confirm that neutral alkyl carboxylic acids are accumulated in the surface region, while charged species, as alkyl carboxylates, are depleted. The XPS studies show also that the hydrophobic alkyl chains are oriented upwards into regions with lower relative permittivity and density, thus perpendicular to the aqueous surface. These combined results show that there are several chemical equilibria between the aqueous bulk and the surface region. The analytical studies show that the release of mainly ammonia is dependent on its concentration in the surface region, as long as the solubility of the carboxylic acid in the surface region is sufficiently high to avoid a precipitation in/on the water-air interface. However, for n-octyl- and n-nonylcarboxylic acid the solubility is sufficiently low to cause precipitation. The combined analytical and surface speciation studies in this work show that the equilibria involving the surface region are fast. The results from this study increase the knowledge about the distribution of chemical species in the surface region at and close to the water-air interface, and the transport of chemicals from water to air in open systems.

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  • 18.
    Burmeister, Florian
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Andersson, L M
    Department of Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Richter, T
    Zimmerman, P
    Godehusen, K
    Karlsson, Hans
    Department of Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Sorensen, S L
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Feifel, Raimund
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Wiesner, Karoline
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Goscinski, Osvaldo
    Department of Quantum Chemistry. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Karlsson, Leif
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    A study of the inner-valence ionization region in HCl and DCl2004In: Journal of Physics B: At. Mol. Opt. Phys., Vol. 37, p. 1173-Article in journal (Refereed)
  • 19.
    Burmeister, Florian
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics II. Physics V.
    Andersson, L. M.
    Öhrwall, Gunnar
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics II. Physics V.
    Richter, T.
    Zimmermann, P.
    Godehusen, K.
    Martins, M.
    Karlsson, H. O.
    Sorensen, S. L
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics II. Physics V.
    Feifel, Reimund
    Wiesner, Karoline
    Goscinsky, O.
    Karlsson, Leif
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics II. Physics V.
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics II. Physics V.
    Yencha, A.
    PES/TPES comparative study of the inner-valence ionization region in HCl and DCl2004In: Journal of Physics B, Vol. 37, p. 1173-Article in journal (Refereed)
  • 20.
    Carravetta, Vincenzo
    et al.
    CNR, IPCF, Inst Chem & Phys Proc, Via G Moruzzi 1, I-56124 Pisa, Italy.
    de Abreu Gomes, Anderson Herbert
    Univ Estadual Campinas, Inst Phys Gleb Wataghin, Dept Appl Phys, BR-13083859 Campinas, SP, Brazil;LNLS, BR-13084971 Campinas, SP, Brazil.
    Monti, Susanna
    CNR, ICCOM, Inst Chem Organometall Cpds, Via G Moruzzi 1, I-56124 Pisa, Italy.
    Mocellin, Alexandra
    Brasilia Univ, Inst Phys, Box 4455, BR-70910970 Brasilia, DF, Brazil.
    Marinho, Ricardo R. T.
    Brasilia Univ, Inst Phys, Box 4455, BR-70910970 Brasilia, DF, Brazil;Univ Fed Bahia, Inst Phys, BR-40170115 Salvador, BA, Brazil.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ågren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. KTH Royal Inst Technol, Theoret Chem & Biol, Sch Chem Biotechnol & Hlth, SE-10044 Stockholm, Sweden.
    de Brito, Arnaldo Naves
    Univ Estadual Campinas, Inst Phys Gleb Wataghin, Dept Appl Phys, BR-13083859 Campinas, SP, Brazil.
    pH-dependent X-ray Photoelectron Chemical Shifts and Surface Distribution of Cysteine in Aqueous Solution2019In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 123, no 17, p. 3776-3785Article in journal (Refereed)
    Abstract [en]

    The distribution and protonation states of amino acids in water droplets are of considerable concern in studies on the formation of clouds in the atmosphere as well as in many biological contexts. In the present work we use the amino acid cysteine as a prototypical example and explore the protonation states of this molecule in aqueous solution, which are strongly affected by the acidity of the environment and also can show different distributions between surface and bulk. We use a combination of X-ray photoelectron chemical shift measurements, density functional theory calculations of the shifts, and reactive force field molecular dynamics simulations of the underlying structural dynamics. We explore how the photoelectron spectra distinctly reflect the different protonation states that are generated by variation of the solution acidity and how the distribution of these protonation states can differ between bulk and surface regions. At specific pH values, we find that the distribution of the cysteine species at the surface is quite different from that in bulk, in particular, for the appearance in the surface region of species which do not exist in bulk. Some ramifications of this finding are discussed.

  • 21.
    Carravetta, Vincenzo
    et al.
    Inst Chem & Phys Proc, CNR IPCF, Via G Moruzzi 1, I-56124 Pisa, Italy..
    de Abreu Gomes, Anderson Herbert
    Campinas Univ, Inst Phys Gleb Wataghin, Dept Appl Phys, BR-13083859 Campinas, SP, Brazil.;Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, POB 6192, BR-13083970 Campinas, SP, Brazil..
    Teixeira Marinho, Ricardo dos Reis
    Univ Fed Bahia, Inst Phys, BR-40170115 Salvador, BA, Brazil.;Brasilia Univ UnB, Inst Phys, BR-70919970 Brasilia, DF, Brazil..
    Ohrwall, Gunnar
    Lund Univ, MAX IV Lab, Box 118, SE-22100 Lund, Sweden..
    Ågren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    de Brito, Arnaldo Naves
    Campinas Univ, Inst Phys Gleb Wataghin, Dept Appl Phys, BR-13083859 Campinas, SP, Brazil..
    An atomistic explanation of the ethanol-water azeotrope2022In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 42, p. 26037-26045Article in journal (Refereed)
    Abstract [en]

    Ethanol and water form an azeotropic mixture at an ethanol molecular percentage of similar to 91% (similar to 96% by volume), which prohibits ethanol from being further purified via distillation. Aqueous solutions at different concentrations in ethanol have been studied both experimentally and theoretically. We performed cylindrical micro-jet photoelectron spectroscopy, excited by synchrotron radiation, 70 eV above C1s ionization threshold, providing optimal atomic-scale surface-probing. Large model systems have been employed to simulate, by molecular dynamics, slabs of the aqueous solutions and obtain an atomistic description of both bulk and surface regions. We show how the azeotropic behaviour results from an unexpected concentration-dependence of the surface composition. While ethanol strongly dominates the surface and water is almost completely depleted from the surface for most mixing ratios, the different intermolecular bonding patterns of the two components cause water to penetrate to the surface region at high ethanol concentrations. The addition of surface water increases its relative vapour pressure, giving rise to the azeotropic behaviour.

  • 22.
    Ekholm, V
    et al.
    Lund Univ, MAX IV Lab, Box 118, SE-22100 Lund, Sweden.;Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden..
    Chiuzbaian, G. S.
    Sorbonne Univ, F-75005 Paris, France.;CNRS, LCPMR, F-75005 Paris, France.;Synchrotron SOLEIL, LOrme Merisiers, BP 48, F-91192 Gif Sur Yvette, France..
    Sathe, C.
    Lund Univ, MAX IV Lab, Box 118, SE-22100 Lund, Sweden..
    Nicolaou, A.
    Synchrotron SOLEIL, LOrme Merisiers, BP 48, F-91192 Gif Sur Yvette, France..
    Guarise, M.
    Sorbonne Univ, F-75005 Paris, France.;CNRS, LCPMR, F-75005 Paris, France.;Ctr Nacl Pesquisa Energia & Mat CNPEM, BR-10000 Campinas, Brazil..
    Simon, M.
    Sorbonne Univ, F-75005 Paris, France.;CNRS, LCPMR, F-75005 Paris, France..
    Jaouen, N.
    Synchrotron SOLEIL, LOrme Merisiers, BP 48, F-91192 Gif Sur Yvette, France..
    Luning, J.
    Sorbonne Univ, F-75005 Paris, France.;CNRS, LCPMR, F-75005 Paris, France..
    Hague, C. F.
    Sorbonne Univ, F-75005 Paris, France.;CNRS, LCPMR, F-75005 Paris, France..
    Gel'mukhanov, F.
    Royal Inst Technol, Sch Biotechnol, Theoret Chem & Biol, S-10691 Stockholm, Sweden.;Siberian Fed Univ, Krasnoyarsk 660041, Russia.;Fed Res Ctr KSC SB RAS, Kirensky Inst Phys, Krasnoyarsk 660036, Russia..
    Odelius, M.
    Stockholm Univ, AlbaNova Univ Ctr, Dept Phys, SE-10691 Stockholm, Sweden..
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Core-hole localization and ultra-fast dissociation in SF62020In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 53, no 18, article id 185101Article in journal (Refereed)
    Abstract [en]

    Resonant inelastic x-ray scattering spectra excited at the fluorine K resonances of SF(6)have been recorded. While a small but significant propensity for electronically parity-allowed transitions is found, the observation of parity-forbidden electronic transitions is attributed to vibronic coupling that breaks the global inversion symmetry of the electronic wavefunction and localizes the core hole. The dependence of the scattering cross section on the polarization of the incident radiation and the scattering angle is interpreted in terms of local pi/sigma symmetry around the S-F bond. This symmetry selectivity prevails during the dissociation that occurs during the scattering process.

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  • 23.
    Ekholm, Victor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Caleman, C
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Molecular biophysics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Walz, Marie-Madeleine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics.
    Werner, Josephina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Öhrwall, Gunnar
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Surface propensity of atmospherically relevant carboxylates and alkyl ammonium ions studied by XPS: towards a building-block model of surface propensity based on Langmuir adsorptionManuscript (preprint) (Other academic)
  • 24.
    Ekholm, Victor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. DESY, Ctr Free Elec Laser Sci, Notkestr 85, DE-22607 Hamburg, Germany.
    Bjärnhall Prytz, Nicklas
    Royal Inst Tech, Dept App Phys, Roslagstullsbacken 21, SE-11421 Stockholm, Sweden.
    Walz, Marie-Madeleine
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics.
    Werner, Josephina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Öhrwall, Gunnar
    Lund Univ, MAX Lab 4, Box 118, SE-22100 Lund, Sweden.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Strong Enrichment of Atmospherically Relevant Organic Ions at the Aqueous Interface: The Role of Ion Pairing and Cooperative Effects2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 42, p. 27185-27191Article in journal (Refereed)
    Abstract [en]

    Surface affinity, orientation and ion pairing are investigated in mixed and single solute systems of aqueous sodium hexanoate and hexylammonium chloride. The surface sensitive X-ray photoelectron spectroscopy technique has been used to acquire the experimental results, while the computational data have been calculated using molecular dynamics simulations. By comparing the single solute solutions with the mixed one, we observe a non-linear surface enrichment and reorientation of the organic ions with their alkyl chains pointing out of the aqueous surface. We ascribe this effect to ion paring between the charged functional groups on the respective organic ion and hydrophobic expulsion of the alkyl chains from the surface in combination with van der Waals interactions between the alkyl chains. These cooperative effects lead to a substantial surface enrichment of organic ions, with consequences for aerosol surface properties.

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  • 25.
    Ekholm, Victor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gråsjö, Johan
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Dong, Minjie
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Såthe, Conny
    Uppsala University.
    Chatzigeorgiou, Evanthia
    Agåker, Marcus
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Harada, Yoshihisa
    Miyawaki, Jun
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Aqueous carbonate and bicarbonate ions studied by RIXS at the O K-edgeManuscript (preprint) (Other academic)
  • 26.
    Ekholm, Victor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. Uppsala Univ, Dept Phys & Astron, POB 516, SE-75120 Uppsala, Sweden.
    Vazdar, Mario
    Rudjer Boskovic Inst, Bijenicka Cesta 54, Zagreb 10000, Croatia.
    Mason, Philip E.
    Acad Sci Czech Republ, Inst Organ Chem & Biochem, Flemingovo Nam 2, CR-16610 Prague 6, Czech Republic.
    Bialik, Erik
    Lund Univ, Dept Chem, Phys Chem, POB 124, SE-22100 Lund, Sweden.
    Walz, Marie-Madeleine
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Computational Biology and Bioinformatics. Uppsala Univ, Dept Cell & Mol Biol Computat Biol & Bioinformat, POB 596, SE-75124 Uppsala, Sweden.
    Ohrwall, Gunnar
    Lund Univ, MAX Lab 4, POB 118, SE-22100 Lund, Sweden.
    Werner, Josephina
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rubensson, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Jungwirth, Pavel
    Acad Sci Czech Republ, Inst Organ Chem & Biochem, Flemingovo Nam 2, CR-16610 Prague 6, Czech Republic.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Anomalous surface behavior of hydrated guanidinium ions due to ion pairing2018In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 148, no 14, article id 144508Article in journal (Refereed)
    Abstract [en]

    Surface affinity of aqueous guanidinium chloride (GdmCl) is compared to that of aqueous tetrapropylammonium chloride (TPACl) upon addition of sodium chloride (NaCl) or disodium sulfate (Na2SO4). The experimental results have been acquired using the surface sensitive technique X-ray photoelectron spectroscopy on a liquid jet. Molecular dynamics simulations have been used to produce radial distribution functions and surface density plots. The surface affinities of both TPA(+) and Gdm(+) increase upon adding NaCl to the solution. With the addition of Na2SO4, the surface affinity of TPA(+) increases, while that of Gdm(+) decreases. From the results of MD simulations it is seen that Gdm(+) and SO42- ions form pairs. This finding can be used to explain the decreased surface affinity of Gdm(+) when co-dissolved with SO42- ions. Since SO42- ions avoid the surface due to the double charge and strong water interaction, the Gdm(+)-SO42- ion pair resides deeper in the solutions' bulk than the Gdm(+) ions. Since TPA(+) does not form ion pairs with SO42-, the TPA(+) ions are instead enriched at the surface.

  • 27.
    Feifel, Raimund
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Andersson, M.
    Öhrwall, Gunnar
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Sorensen, S. L.
    Piancastelli, Maria-Novella
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Karlsson, Leif
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    A quantitative analysis of the N 1s ­> p* photoabsorption profile in N2: new spectroscopic constants for the core-excited state2004In: Chemical Physics Letters, Vol. 383, no 3-4, p. 222-229Article in journal (Refereed)
  • 28.
    Feifel, Raimund
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Baev, A.
    Gelmukhanov, F.
    Ågren, H.
    Andersson, M.
    Öhrwall, Gunnar
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Piancastelli, Maria-Novella
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Miron, C.
    Sorensen, S. L.
    Naves de Brito, A.
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Karlsson, Leif
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Role of stray light in the formation of high-resolution resonant photoelectron spectra: An experimental an theoretical study2004In: Journal of Electron Spectroscopy Relat. Phenom., Vol. 134, no 1, p. 49-Article in journal (Refereed)
  • 29.
    Feifel, Raimund
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Baev, A.
    Gelmukhanov, Faris
    Ågren, Hans
    Piancastelli, Maria-Novella
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Andersson, M.
    Öhrwall, Gunnar
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Miron, C.
    Sorensen, S. L.
    Naves de Brito, A.
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Karlsson, Leif
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Generalization of the duration time concept for interpreting high resolution resonant photoemission spectra2004In: Physical Review A, Vol. 69, p. 022707-Article in journal (Refereed)
  • 30.
    Feifel, Raimund
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics.
    Gel´mukhanov, F
    Baev, A
    Ågren, H
    Piancastelli, Maria Novella
    Bässler, M
    Miron, C
    Sorensen, Stacey L
    Naves de Brito, Arnaldo
    Björneholm, Olle
    Karlsson, Leif
    Svensson, Svante
    Interference Quenching of v2002In: Physical Review Letters, Vol. 89, no 10, p. 103002-1Article in journal (Refereed)
  • 31.
    Feifel, Raimund
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Karlsson, Leif
    Department of Physics and Materials Science, Physics V.
    Piancastelli, Maria Novella
    Department of Physics and Materials Science, Physics V.
    Fink, R F
    Bässler, M
    Björneholm, Olle
    Department of Physics and Materials Science, Physics V.
    Wiesner, Karoline
    Miron, C
    Wang, H
    Giertz, Annica
    Sorensen, Stacey L
    Naves de Brito, Arnaldo
    Svensson, Svante
    Department of Physics and Materials Science, Physics V.
    "Hidden" vibrations in CO: Reinvestigation of resonant Auger decay for the C 1s ->pi* excitation2002In: Physical Review A, Vol. 65, no 5, p. 052701-Article in journal (Refereed)
  • 32.
    Feifel, Raimund
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Tchaplyguine, Maxim
    Öhrwall, Gunnar
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Lundwall, Marcus
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Marinho, Ricardo
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Gisselbrecht, M.
    Sorensen, S. L.
    Naves de Brito, A.
    Karlsson, Leif
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Mårtensson, Nils
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V. Physics II.
    From localised to delocalised electronic states in free Ar, Kr and Xe clusters2004In: The European Physical Journal D, Vol. 30, no 3, p. 343-351Article in journal (Refereed)
  • 33.
    Fink, Reinhold
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Eschner, Annika
    Magnuson, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Hjelte, Ingela
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Miron, Catalin
    Bässler, Margit
    Svensson, Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Piancastelli, Maria Novella
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
    Sorensen, Stacey
    Specific production of very long-lived core-excited sulfur atoms by 2p(-1)sigma* excitation of the OCS molecule followed by ultrafast dissociation2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 12, p. L269-L275Article in journal (Refereed)
    Abstract [en]

    A core-excited sulfur state with a lifetime almost one order of magnitude longer than in molecular 2p core-hole states is selectively produced by ultrafast dissociation of S 2p -> sigma* excited OCS. Clear evidence for this is provided by strong atomic peaks (20% of the total intensity) in x-ray fluorescence but very weak ones (2%) in the corresponding resonant Auger spectrum. Corroborating the assignment of the spectra, ab initio calculations explain the enhanced lifetime: the Auger decay of the produced D-3(3) (2p(5)3p(5)) sulfur state is strongly decreased as it contradicts a newly derived propensity rule of the L2,3MM Auger decay.

  • 34. Gisselbrecht, M.
    et al.
    Grunewald, C.
    Månsson, E.
    Laksman, J.
    Sankari, A.
    Tchaplyguine, M.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Sorensen, S. L.
    Charge migration and decay of doubly charged ammonia clusters2012In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 388, no 2, p. 022112-Article in journal (Refereed)
    Abstract [en]

    The photo-fragmentation of ammonia molecular clusters ionized with soft x-rays is studied for photon energies near the N-1s threshold. The fragmentation is studied with a 3D momentum mass spectrometer to access the energy and angular correlations between fragments. By choosing the cluster sizes below or above the critical size of stable dication, we investigate the coulomb explosion dynamics and the interplay between charge delocalization and mobility of molecules in the clusters.

  • 35. Gisselbrecht, Mathieu
    et al.
    Lindgren, Andreas
    Tchaplyguine, Maxim
    Burmeister, Florian
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Öhrwall, Gunnar
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Lundwall, Marcus
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Lundin, Magnus
    Marinho, Ricardo R. T.
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Naves de Brito, Arnaldo
    Svensson, Svante
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Björneholm, Olle
    Department of Physics. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Materials Science, Physics V.
    Sorensen, Stacey L.
    Photon energy dependence of fragmentation of small argon clusters2005In: J. Chem. Phys., Vol. 123, p. 194301-Article in journal (Refereed)
  • 36.
    Gopakumar, G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Unger, I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. DESY, FS BIG, Hamburg, Germany..
    Slavicek, P.
    Univ Chem & Technol, Dept Phys Chem, Prague, Czech Republic..
    Hergenhahn, U.
    Oehrwall, G.
    Lund Univ, MAX Lab 4, Lund, Sweden..
    Malerz, S.
    Fritz Haber Inst Max Planck Gesell, Berlin, Germany..
    Ceolin, D.
    Synchrotron SOLEIL, LOrme Merisiers, Paris, France..
    Trinter, F.
    Fritz Haber Inst Max Planck Gesell, Berlin, Germany.;Goethe Univ Frankfurt Main, Inst Kernphys, Frankfurt, Germany..
    Winter, B.
    Fritz Haber Inst Max Planck Gesell, Berlin, Germany..
    Wilkinson, I.
    Helmholtz Zentrum Berlin Mat & Energie, Inst Elect Struct Dynam, Berlin, Germany..
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. DESY, Ctr Free Elect Laser Sci, Hamburg, Germany..
    Muchova, E.
    Univ Chem & Technol, Dept Phys Chem, Prague, Czech Republic..
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Radiation damage by extensive local water ionization from two-step electron-transfer-mediated decay of solvated ions2023In: Nature Chemistry, ISSN 1755-4330, E-ISSN 1755-4349, Vol. 15, no 10, p. 1408-+Article in journal (Refereed)
    Abstract [en]

    Biomolecular radiation damage is largely mediated by radicals and low-energy electrons formed by water ionization rather than by direct ionization of biomolecules. It was speculated that such an extensive, localized water ionization can be caused by ultrafast processes following excitation by core-level ionization of hydrated metal ions. In this model, ions relax via a cascade of local Auger-Meitner and, importantly, non-local charge- and energy-transfer processes involving the water environment. Here, we experimentally and theoretically show that, for solvated paradigmatic intermediate-mass Al3+ ions, electronic relaxation involves two sequential solute-solvent electron transfer-mediated decay processes. The electron transfer-mediated decay steps correspond to sequential relaxation from Al5+ to Al3+ accompanied by formation of four ionized water molecules and two low-energy electrons. Such charge multiplication and the generated highly reactive species are expected to initiate cascades of radical reactions.

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  • 37.
    Gopakumar, Geethanjali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Muchova, E
    Department of Physical Chemistry, University of Chemistry and Technology, Technick ́a 5, Prague 6, 166 28, Czech Republic.
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Malerz, S
    Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
    Trinter, F
    Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
    Öhrwall, G
    MAX IV Laboratory, Lund University, Box 118, SE-22100 Lund, Sweden.
    Lipparini, F
    Department of Chemistry and Industrial Chemistry, University of Pisa, Via Giuseppe Moruzzi 13, 56124 Pisa, Italy.
    Menucci, B
    Department of Chemistry and Industrial Chemistry, University of Pisa, Via Giuseppe Moruzzi 13, 56124 Pisa, Italy.
    Ceolin, D
    Synchrotron SOLEIL, L’Orme des Merisiers Saint-Aubin, BP 48 91192 Gif-sur-Yvette Cedex, Paris, France.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Wilkinson, I
    Department of Locally-Sensitive Time-Resolved Spectroscopy, Helmholtz-Zentrum Berlin fur Materialien und Energie, 14109 Berlin, Germany.
    Winter, B
    Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
    Slavicek, P
    Department of Physical Chemistry, University of Chemistry and Technology, Technick ́a 5, Prague 6, 166 28, Czech Republic.
    Hergenhahn, U
    Molecular Physics Department, Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Probing Aqueous Ions with Non-local Auger Relaxation2022In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 24, no 15, p. 8661-8671Article in journal (Refereed)
    Abstract [en]

    The decay of core holes is often regarded as a local process, but in some systems, it involves the autoionization of neighbouring atoms or molecules. Here, we explore such non-local autoionization (Intermolecular Coulombic Decay, ICD) of surrounding molecules upon 1s ionization of aqueous-phase Na+, Mg2+ and Al3+ ions. The three ions are isoelectronic but differ in the strength of the ion-water interactions which is manifested in experimental Auger electron spectra by varying intensities. While for strongly interacting Mg2+ and Al3+ the non-local decay is observed, for weakly bound Na+ no signal was measured. Combined with theoretical simulations we provide a microscopic understanding of the non-local decay processes. We assigned the ICD to decay processes ending with two-hole states delocalized between the central ion and neighbouring water. The ICD process is also shown to be highly selective with respect to water molecular orbitals. The ICD lifetime was estimated to be around 40 fs for Mg and 20 fs for Al. Auger spectroscopy thus represents a novel tool for exploring molecules in the liquid phase, providing simultaneously structural and electronic information.   

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  • 38.
    Gopakumar, Geethanjali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Svensson, Pamela
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Grånäs, Oscar
    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, Physics, Department of Physics and Astronomy, Theoretical Physics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Schwob, Lucas
    Deutsch Elektronen Synchrotron DESY, DE-22607 Hamburg, Germany..
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Saak, Clara-Magdalena
    Univ Vienna, Dept Phys Chem, A-1090 Vienna, Austria..
    Timm, Martin
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, DE-12489 Berlin, Germany.;Tech Univ Berlin, Inst Opt & Atomare Phys, DE-10623 Berlin, Germany..
    Buelow, Christine
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, DE-12489 Berlin, Germany.;Albert Ludwigs Univ Freiburg, Phys Inst, DE-79104 Freiburg, Germany..
    Kubin, Markus
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, DE-12489 Berlin, Germany..
    Zamudio-Bayer, Vicente
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, DE-12489 Berlin, Germany..
    Lau, J. Tobias
    Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, DE-12489 Berlin, Germany.;Albert Ludwigs Univ Freiburg, Phys Inst, DE-79104 Freiburg, Germany..
    von Issendorff, Bernd
    Albert Ludwigs Univ Freiburg, Phys Inst, DE-79104 Freiburg, Germany..
    Abid, Abdul Rahman
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Univ Oulu, Fac Sci, Nano & Mol Syst Res Unit, Oulu 90570, Finland..
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Danielsson, Emma
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Koerfer, Ebba
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Deutsch Elektronen Synchrotron DESY, Ctr Free Electron Laser Sci, DE-22607 Hamburg, Germany..
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. Helmholtz Zentrum Berlin Mat & Energie, Abt Hochempfindl Rontgenspektroskopie, DE-12489 Berlin, Germany.;Lund Univ, Dept Phys, SE-22100 Lund, Sweden.;Uppsala Univ, Dept Chem, Angstrom Lab, SE-75121 Uppsala, Sweden..
    X-ray Induced Fragmentation of Protonated Cystine2022In: Journal of Physical Chemistry A, ISSN 1089-5639, E-ISSN 1520-5215, Vol. 126, no 9, p. 1496-1503Article in journal (Refereed)
    Abstract [en]

    We demonstrate site-specific X-ray induced fragmentation across the sulfur L-edge of protonated cystine, the dimer of the amino acid cysteine. Ion yield NEXAFS were performed in the gas phase using electrospray ionization (ESI) in combination with an ion trap. The interpretation of the sulfur Ledge NEXAFS spectrum is supported by Restricted Open-Shell Configuration Interaction (ROCIS) calculations. The fragmentation pathway of triply charged cystine ions was modeled by Molecular Dynamics (MD) simulations. We have deduced a possible pathway of fragmentation upon excitation and ionization of S 2p electrons. The disulfide bridge breaks for resonant excitation at lower photon energies but remains intact upon higher energy resonant excitation and upon ionization of S 2p. The larger fragments initially formed subsequently break into smaller fragments.

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  • 39.
    Gopakumar, Geethanjali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Svensson, Pamela H.W.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Grånäs, Oscar
    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.
    Schwob, L
    Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Saak, Clara-Magdalena
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Timm, M
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, DE-12489 Berlin, Germany; nstitut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, DE-10623 Berlin, Germany.
    Bülow, C
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, DE-12489 Berlin, Germany; Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 3, DE-79104 Freiburg, Germany.
    Kubin, M
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, DE-12489 Berlin, Germany.
    Zamudio-Bayer, V
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, DE-12489 Berlin, Germany.
    Lau, J-T
    Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, DE-12489 Berlin, Germany; Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 3, DE-79104 Freiburg, Germany.
    von Issendorff, B
    Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 3, DE-79104 Freiburg, Germany.
    Abid, Abdul Rahman
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Nano and Molecular Systems Research Unit, Faculty of Science, University of Oulu, P. O. Box 3000, Finland.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Danielsson, E
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Koerfer, E
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Department of Physics, Lund University, Box 118, SE-22100 Lund, Sweden; Abteilung für Hochempfindliche Röntgenspektroskopie, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, DE-12489 Berlin, Germany.
    X-ray Induced Fragmentation of Protonated CystineManuscript (preprint) (Other academic)
    Abstract [en]

    Protein structure determination using high-intensity X-ray sources induces damage in the protein. Disulfide bridges, formed between two cysteine amino acid residues stabilize the protein structure. Owing to the higher absorption cross-section of sulfur for X-ray photons, and a large number of electrons released from sulfur atoms, these disulfide bridges are hot spots for a higher level of noise in structural studies. But it is yet to be understood how exactly the damage occurs through the interaction of the disulfide bridges with photons. Here we study the fragmentation of protonated cystine in the gas phase, which is the dimer of cysteine, by irradiation with X-rays across the sulfur L-edge using an electrospray ionization source (ESI) in combination with an ion trap. This is complemented with the calculation of the sulfur NEXAFS spectrum on the level of Restricted Open-Shell Configuration Interaction (ROCIS) and Density Functional Theory (DFT) calculations for molecular orbital visualization as well as Molecular Dynamics (MD) simulations for the fragmentation of triply charged cystine ions. We have deduced a possible pathway of fragmentation upon excitation and ionization of S 2p electrons by combining the experiments and simulations. The disulfide bridge breaks for resonant excitation at lower energies but remains intact upon higher energy resonant excitation and upon ionization of S 2p. The larger fragments formed subsequently break into smaller fragments. 

  • 40.
    Gopakumar, Geethanjali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Saak, Clara-Magdalena
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Öhrwall, Gunnar
    MAX IV Laboratory, Lund University, PO Box 118, SE-22100 Lund, Sweden.
    Naves de Brito, Arnaldo
    University of Campinas, Campinas, SP, Brazil.
    Costa Rizuti da Rocha, Tulio
    Brazilian Synchrotron Light Laboratory (LNLS), Brazilian Center for Research in Energy and Materials (CNPEM), Sao Paulo, Brazil.
    Nicolas, Christophe
    Synchrotron SOLEIL, Gif-sur-Yvette, France.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    The Surface Composition of Amino Acid - Halide Salt Solutions is pH-Dependent2022In: Environmental Science: Atmospheres, no 3Article in journal (Refereed)
    Abstract [en]

    In atmospheric aerosol particles, the chemical surface composition governs both heterogeneous chemical reactions with gas-phase species and the ability to act as nuclei for cloud droplets. The pH in aerosol droplets is expected to affect these properties, but it is very challenging to measure the pH in individual droplets, precluding the investigation of its influence on the particle's surface composition. In this work, we use photoelectron spectroscopy to explore how the surface composition of aqueous solutions containing inorganic salt and amino acids changes as a function of pH. We observe a change by a factor of 4-5 of the relative distribution of inorganic ions at the surface of a liquid water jet, as a function of solution pH and type of amino acid in the solution. The driving forces for the surface enhancement or depletion are ion pairing and the formation of charged layers close to the aqueous surface. Our findings apply to any aqueous interface at which organic species with charged functional groups are present.

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  • 41. Gopakumar, Geethanjali
    et al.
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Öhrwall, G
    MAX IV Laboratory, Fotongatan 2, 221 00 Lund, Sweden.
    Malerz, S
    Molecular Physics Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4, 14195 Berlin, Germany.
    Ceolin, D
    Trinter, F
    Molecular Physics Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4, 14195 Berlin, Germany.
    Chatzigeorgiou, Evanthia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Winter, B
    Molecular Physics Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4, 14195 Berlin, Germany.
    Caleman, Carl
    Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    X-ray-induced attosecond ion-water electron dynamics of aqueous ionsManuscript (preprint) (Other academic)
    Abstract [en]

    The foundation of many physical and chemical processes is the transfer of charge from one entity to another. In many cases, the charge transfer is mediated by electron transfer and due to the comparatively low mass of electrons, these processes tend to take place within a few femtoseconds or several attoseconds. We investigate the charge transfer from Na+, Mg2+ and Al3+ in an aqueous environment to neighbouring water molecules. In order to achieve this, we use the core-hole clock method and Auger spectroscopy upon 1s ionization of the respective ions. The charge transfer times range from several 100 as below the 1s ionization threshold to only 20 as far above the 1s ionization. The decrease in charge transfer times as a function of the photon energy seems to be continuous. Despite the ions being isoelectronic in our study, we nd differences in their charge transfer behaviour.

  • 42.
    Gopakumar, Geethanjali
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Unger, Isaak
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, Germany.
    Öhrwall, I
    MAX IV Laboratory, Fotongatan 2, 221 00 Lund, Sweden.
    Malerz, S
    olecular Physics Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4, 14195 Berlin, Germany.
    Ceolin, D
    Synchrotron SOLEIL, L’Orme des Merisiers Saint-Aubin, BP 48 91192 Gif-sur-Yvette Cedex, Paris, France.
    Trinter, F
    olecular Physics Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4, 14195 Berlin, Germany.
    Winter, B
    olecular Physics Department, Fritz Haber Institute of the Max Planck Society, Faradayweg 4, 14195 Berlin, Germany.
    Caleman, Carl
    Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg, German.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Non-local decay of highly charged aqueous inorganic ions produced by Auger decayManuscript (preprint) (Other academic)
    Abstract [en]

    High-Z atoms are more important for biological radiation damage by photons than their low abundance due to their higher photoionization cross-section. Using the inorganic Mg 2+ and Al3+ ions in water as model systems, we have studied decay processes following deep core-level ionization. Local Auger decay rapidly produces highly charged Mg 4+and Al5+ ions, the decay of which must involve non-local processes involving the surrounding water, such as electron transfer mediated decay (ETMD). Using electron spectroscopy we observe two distinct ETMD decay steps for Al, corresponding to decay from Al5+ to Al4+, and then from Al4+ to Al3+. The ETMD energetics is discussed using both a simple model and calculations. Contrary to expectations, we do not observe any ETMD for Mg, and possible reasons for this are discussed.

  • 43.
    Grånäs, Oscar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Mocellin, A.
    Brasilia Univ, Inst Phys, Brasilia, DF, Brazil..
    Cardoso, E. S.
    Lab Nacl Luz Sincrotron, Box 6192, BR-13083970 Campinas, SP, Brazil.;Univ Estadual Campinas, Rua Sergio Buarque Holanda 777,Cidade Univ, BR-13083970 Campinas, SP, Brazil..
    Burmeister, Florian
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Caleman, Carl
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics. DESY, Ctr Free Electron Laser Sci, Notkestr 85, DE-22607 Hamburg, Germany..
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Naves de Brito, A.
    Univ Estadual Campinas, Rua Sergio Buarque Holanda 777,Cidade Univ, BR-13083970 Campinas, SP, Brazil..
    Femtosecond fragmentation of CS2 after sulfur 1s ionization: interplay between Auger cascade decay, charge delocalization, and nuclear motion2020In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 53, no 24, article id 244007Article in journal (Refereed)
    Abstract [en]

    We present a combined experimental and theoretical study of the fragmentation of molecular CS2 after sulfur 1s Auger cascade decay, consisting of electron-multi-ion coincidence spectra of charged fragments and theoretical simulations combining density functional theory and molecular dynamics. On the experimental side, a procedure for a complete determination of all sets of ions formed is described. For many of the fragmentation channels, we observed a higher charge in one of the sulfur atoms than the other atoms. Based on these observations and the theoretical simulations where the time scale of the nuclear motion and decay is taken into account, we propose that KLL Auger decay after the 1s core hole creation, via 2p double hole states, results in highly charged and strongly repulsive states with one localized core hole. These localized core holes are sufficiently long-lived that some will decay after fragmentation of the molecular ion, thereby efficiently impeding charge exchange between the fragments.

  • 44. Harnes, J.
    et al.
    Abu-samha, M.
    Bergersen, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Winkler, M.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Saethre, L. J.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Borve, K. J.
    The structure of mixed methanol/chloroform clusters from core-level photoelectron spectroscopy and modeling2011In: New Journal of Chemistry, ISSN 1144-0546, E-ISSN 1369-9261, Vol. 35, no 11, p. 2564-2572Article in journal (Refereed)
    Abstract [en]

    Mixed neutral molecular clusters have been produced by co-expansion of chloroform and methanol and characterized by carbon 1s photoelectron spectroscopy and theoretical modeling. The produced clusters are in the range 50-150 molecules and the clusters are not homogeneously mixed: chloroform is enriched in the bulk and methanol is found on or close to the surface. This is based on evidence from photoelectron depth profiling and molecular dynamics simulations of mixed clusters. The simulations suggest that methanol forms cyclic or linear oligomers in the surface layers of the mixed clusters. From thermodynamic models, the enrichment of methanol on the cluster surface can be rationalized from the difference in surface tension between the two pure components, which is connected to the qualitative differences in the respective bonding patterns.

  • 45.
    Hjelte, Ingela
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Björneholm, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Carravetta, V.
    Angeli, C.
    Cimiraglia, R.
    Wiesner, K.
    Svensson, Svante
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Piancastelli, Maria Novella
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Constant-atomic-final-state filtering of dissociative states in the O1sŮɖ* core excitation in O22005In: J. Chem. Phys., Vol. 123, p. 06431-Article in journal (Refereed)
  • 46. Jankala, K.
    et al.
    Tchaplyguine, M.
    Mikkela, M.-H.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Surface and Interface Science.
    Huttula, M.
    Photon Energy Dependent Valence Band Response of Metallic Nanoparticles2011In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 107, no 18, p. 183401-Article in journal (Refereed)
    Abstract [en]

    We show that the valence band response to photon impact in metallic nanoparticles is highly energy dependent. This is seen as drastic variations of cross sections in valence photoionization of free and initially charge-neutral nanosized metal clusters. The effect is demonstrated in a combined experimental and theoretical study of Rb clusters. The experimental findings are interpreted theoretically using a jellium model and superatom description. The variations are attributed to the changing overlap with the photon energy between the wave functions of diffuse delocalized valence electrons and continuum electrons producing a series of minima in the cross section.

  • 47. Jena, Naresh K.
    et al.
    Josefsson, Ida
    Eriksson, Susanna Kaufmann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Odelius, Michael
    Solvent-Dependent Structure of the I-3(-) Ion Derived from Photoelectron Spectroscopy and Ab Initio Molecular Dynamics Simulations2015In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 21, no 10, p. 4049-4055Article in journal (Refereed)
    Abstract [en]

    Ab initio molecular dynamics (MD) simulations of the solvation of LiI3 in four different solvents (water, methanol, ethanol, and acetonitrile) are employed to investigate the molecular and electronic structure of the I-3(-) ion in relation to X-ray photoelectron spectroscopy (XPS). Simulations show that hydrogen-bond rearrangement in the solvation shell is coupled to intramolecular bond-length asymmetry in the I-3(-) ion. By a combination of charge analysis and I 4d core-level XPS measurements, the mechanism of the solvent-induced distortions has been studied, and it has been concluded that charge localization mediates intermolecular interactions and intramolecular distortion. The approach involving a synergistic combination of theory and experiment probes the solvent-dependent structure of the I-3(-) ion, and the geometric structure has been correlated with the electronic structure.

  • 48. Josefsson, Ida
    et al.
    Eriksson, Susanna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ottosson, Niklas
    Ohrwall, Gunnar
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Odelius, Michael
    Collective hydrogen-bond dynamics dictates the electronic structure of aqueous I-3(-)2013In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, no 46, p. 20189-20196Article in journal (Refereed)
    Abstract [en]

    The molecular and electronic structures of aqueous I-3 and I ions have been investigated through ab initio molecular dynamics (MD) simulations and photoelectron (PE) spectroscopy of the iodine 4d core levels. Against the background of the theoretical simulations, data from our I4d PE measurements are shown to contain evidence of coupled solute-solvent dynamics. The MD simulations reveal large amplitude fluctuations in the I-I distances, which couple to the collective rearrangement of the hydrogen bonding network around the I-3(-) ion. Due to the high polarizability of the I-3(-) ion, the asymmetric I-I vibration reaches partially dissociated configurations, for which the electronic structure resembles that of I-2 + I-. The charge localization in the I-3(-) ion is found to be moderated by hydrogen-bonding. As seen in the PE spectrum, these soft molecular vibrations are important for the electronic properties of the I-3(-) ion in solution and may play an important role in its electrochemical function.

  • 49.
    Kirschner, Johannes
    et al.
    AMOLF, Ultrafast Spect, 1098 XG Sci Pk, Amsterdam, Netherlands.
    Gomes, Anderson H. A.
    Univ Estadual Campinas, Inst Phys Gleb Wataghin, Dept Appl Phys, BR-13083859 Campinas, SP, Brazil.
    Marinho, Ricardo R. T.
    Univ Fed Bahia, Inst Phys, BR-40170115 Salvador, BA, Brazil; Brasilia Univ, Inst Phys, Box 4455, BR-70910970 Brasilia, DF, Brazil.
    Björneholm, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics.
    Ågren, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Chemical and Bio-Molecular Physics. Henan Univ, Coll Chem & Chem Engn, Kaifeng 475004, Henan, Peoples R China.
    Carravetta, Vincenzo
    CNR, IPCF, Inst Chem & Phys Proc, Via G Moruzzi 1, I-56124 Pisa, Italy.
    Ottosson, Niklas
    ARCNL, EUV Photoemiss, 1098 XG Sci Pk, Amsterdam, Netherlands.
    Naves de Brito, Arnaldo
    Univ Estadual Campinas, Inst Phys Gleb Wataghin, Dept Appl Phys, BR-13083859 Campinas, SP, Brazil.
    Bakker, Huib J.
    AMOLF, Ultrafast Spect, 1098 XG Sci Pk, Amsterdam, Netherlands.
    The molecular structure of the surface of water-ethanol mixtures2021In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 23, no 19, p. 11568-11578Article in journal (Refereed)
    Abstract [en]

    Mixtures of water and alcohol exhibit an excess surface concentration of alcohol as a result of the amphiphilic nature of the alcohol molecule, which has important consequences for the physico-chemical properties of water-alcohol mixtures. Here we use a combination of intensity vibrational sum-frequency generation (VSFG) spectroscopy, heterodyne-detected VSFG (HD-VSFG), and core-level photoelectron spectroscopy (PES) to investigate the molecular properties of water-ethanol mixtures at the air-liquid interface. We find that increasing the ethanol concentration up to a molar fraction (MF) of 0.1 leads to a steep increase of the surface density of the ethanol molecules, and an increased ordering of the ethanol molecules at the surface. When the ethanol concentration is further increased, the surface density of ethanol remains more or less constant, while the orientation of the ethanol molecules becomes increasingly disordered. The used techniques of PES and VSFG provide complementary information on the density and orientation of ethanol molecules at the surface of water, thus providing new information on the molecular-scale properties of the surface of water-alcohol mixtures over a wide range of compositions. This information is invaluable in understanding the chemical and physical properties of water-alcohol mixtures.

  • 50. Kivimäki, A.
    et al.
    Sorensen, S. L.
    Tchaplyguine, M.
    Gisselbrecht, M.
    Marinho, R. R. T.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Feifel, Reimund
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Öhrwall, Gunnar
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Svensson, Svante
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Björneholm, Olle
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics. Department of Physics and Materials Science, Physics V.
    Resonant Auger spectroscopy of argon clusters at the 2p threshold2005In: Phys. Rev. A, Vol. 71, p. 033204-Article in journal (Refereed)
123 1 - 50 of 137
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