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Bergersen, Henrik
Publications (10 of 18) Show all publications
Bergersen, H., Marinho, R. R., Pokapanich, W., Björneholm, O., Sæthre, L. J., Lindblad, A. & Öhrwall, G. (2007). A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide. Journal of Physics: Condensed Matter, 19(32), 326101
Open this publication in new window or tab >>A photoelectron spectroscopic study of aqueous tetrabutylammonium iodide
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2007 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 19, no 32, p. 326101-Article in journal (Refereed) Published
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.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-97066 (URN)10.1088/0953-8984/19/32/326101 (DOI)000248185800005 ()
Available from: 2008-04-18 Created: 2008-04-18 Last updated: 2017-12-14
Tchaplyguine, M., Peredkov, S., Rosso, A., Schulz, J., Öhrwall, G., Lundwall, M., . . . Björneholm, O. (2007). Direct observation of the non-supported metal nanoparticle electron density of states by X-ray photoelectron spectroscopy. European Physical Journal D: Atomic, Molecular and Optical Physics, 45(2), 295-299
Open this publication in new window or tab >>Direct observation of the non-supported metal nanoparticle electron density of states by X-ray photoelectron spectroscopy
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2007 (English)In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 45, no 2, p. 295-299Article in journal (Refereed) Published
Abstract [en]

Synchrotron-based X-ray photoelectron spectroscopy on copper and silver cluster beams created by a magnetron-based gas-aggregation source has allowed mapping the electron density of states (DOS) of free metallic nanoparticles. The cluster DOS profiles obtained in the experiments strongly resemble the infinite solid DOS shapes, but the extracted cluster work-functions are lower than those for the bulk metal. The latter observation is explained by the initial negative charge on most of the clusters, created by the source.

Keywords
73.22.-f Electronic structure of nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals - 79.60.-i Photoemission and photoelectron spectra
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-97639 (URN)10.1140/epjd/e2007-00252-0 (DOI)000250136000014 ()
Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2017-12-14
Peredkov, S., Öhrwall, G., Schulz, J., Lundwall, M., Rander, T., Lindblad, A., . . . Tchaplyguine, M. (2007). Free nanoscale sodium clusters studied by core-level photoelectron spectroscopy. Physical Review B. Condensed Matter and Materials Physics, 75(23), 235407
Open this publication in new window or tab >>Free nanoscale sodium clusters studied by core-level photoelectron spectroscopy
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2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 75, no 23, p. 235407-Article in journal (Refereed) Published
Abstract [en]

Free sodium metal clusters have been studied by probing the Na2p core level using x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The development of electronic structure with size has been studied and discussed in comparison with the atom, dimer, and solid. Information on cluster metallic properties, size, and temperature has been deduced from the XPS measurements. For the large ⟨N⟩>103 Na clusters, the surface and bulk sites have been separated in the photoelectron signal. Auger spectra allowed extracting the information on the valence band. The present study introduces core-level spectroscopies XPS and AES into the field of free neutral metal cluster research.

Keywords
Nanoscale materials, Clusters, Atomic and molecular clusters, Photoemission and photoelectron spectra
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-97637 (URN)10.1103/PhysRevB.75.235407 (DOI)000247624900112 ()
Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2017-12-14
Lundwall, M., Pokapanich, W., Bergersen, H., Lindblad, A., Rander, T., Öhrwall, G., . . . Björneholm, O. (2007). Self-assembled heterogeneous argon/neon core-shell clusters studied by photoelectron spectroscopy. Journal of Chemical Physics, 126(21), 214706
Open this publication in new window or tab >>Self-assembled heterogeneous argon/neon core-shell clusters studied by photoelectron spectroscopy
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2007 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 126, no 21, p. 214706-Article in journal (Refereed) Published
Abstract [en]

Clusters formed by a coexpansion process of argon and neon have been studied using synchrotron radiation. Electrons from interatomic Coulombic decay as well as ultraviolet and x-ray photoelectron spectroscopy were used to determine the heterogeneous nature of the clusters and the cluster structure. Binary clusters of argon and neon produced by coexpansion are shown to exhibit a core-shell structure placing argon in the core and neon in the outer shells. Furthermore, the authors show that 2 ML of neon on the argon core is sufficient for neon valence band formation resembling the neon solid. For 1 ML of neon the authors observe a bandwidth narrowing to about half of the bulk value.

Keywords
Spectroscopy and geometrical structure of clusters, Electronic structure of nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals, Photoemission and photoelectron spectra
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-96750 (URN)10.1063/1.2735607 (DOI)000247106600033 ()
Available from: 2008-02-28 Created: 2008-02-28 Last updated: 2017-12-14
Peredkov, S., Sorensen, S. L., Rosso, A., Öhrwall, G., Lundwall, M., Rander, T., . . . Tchaplyguine, M. (2007). Size determination of free metal clusters by core-level photoemission from different initial charge states. Physical Review B. Condensed Matter and Materials Physics, 76(8), 081402
Open this publication in new window or tab >>Size determination of free metal clusters by core-level photoemission from different initial charge states
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2007 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 76, no 8, p. 081402-Article in journal (Refereed) Published
Abstract [en]

We present the study of free nanoscale lead clusters using photoelectron spectroscopy and synchrotron radiation. Pb  5d core-level spectra reveal the presence of different initial charge states of the clusters created by the magnetron-based source. We suggest a method for determining the cluster size from the charge-dependent core level binding energies. Both the core-level and the valence spectra demonstrate that we have created free metallic clusters with essentially the same electronic structure as the solid.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-97638 (URN)10.1103/PhysRevB.76.081402 (DOI)000249155400008 ()
Available from: 2008-10-23 Created: 2008-10-23 Last updated: 2017-12-14
Schulz, J., Heinäsmäki, S., Sankari, R., Rander, T., Lindblad, A., Bergersen, H., . . . Aksela, H. (2006). Characterisation of weakly excited final states by shakedown spectroscopy of laser excited potassium. Phys. Rev. A, 74, 12705
Open this publication in new window or tab >>Characterisation of weakly excited final states by shakedown spectroscopy of laser excited potassium
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2006 (English)In: Phys. Rev. A, Vol. 74, p. 12705-Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-84263 (URN)
Available from: 2006-11-14 Created: 2006-11-14 Last updated: 2017-01-25
Bergersen, H., Abu-samha, M., Lindblad, A., Marinho, R., Céolin, D., Öhrwall, G., . . . Björneholm, O. (2006). First observation of vibrations in core-level photoelectron spectra of free neutral molecular clusters. Chemical Physics Letters, 429(1-3), 109-113
Open this publication in new window or tab >>First observation of vibrations in core-level photoelectron spectra of free neutral molecular clusters
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2006 (English)In: Chemical Physics Letters, ISSN 0009-2614, E-ISSN 1873-4448, Vol. 429, no 1-3, p. 109-113Article in journal (Refereed) Published
Abstract [en]

Core-level photoelectron spectra of free neutral methane clusters have been recorded. These spectra exhibit well-resolved surface and bulk features as well as vibrational fine structure. The vibrational structure in the cluster signal is well reproduced by a theoretical model that assumes independent contributions from inter- and intramolecular modes. The intramolecular contribution to the vibrational line-shape is taken to be equal to that of the monomer in the gas phase, while the intermolecular part is simplified to line broadening. An estimate of the cluster size has been made on the basis of the observed surface-to-bulk intensity ratio.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-97061 (URN)10.1016/j.cplett.2006.08.034 (DOI)000241018800020 ()
Available from: 2008-04-18 Created: 2008-04-18 Last updated: 2017-12-14Bibliographically approved
Abu.samha, M., Börve, K. J., Saethre, L. J., Öhrwall, G., Bergersen, H., Rander, T., . . . Tchaplyguine, M. (2006). Lineshapes in carbon 1s photoelectron spectra of methanol clusters. Physical Chemistry Chemical Physics, 21, 2473
Open this publication in new window or tab >>Lineshapes in carbon 1s photoelectron spectra of methanol clusters
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2006 (English)In: Physical Chemistry Chemical Physics, Vol. 21, p. 2473-Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-83603 (URN)
Available from: 2006-11-07 Created: 2006-11-07 Last updated: 2011-01-11
Tchaplyguine, M., Peredkov, S., Svensson, H., Schulz, J., Öhrwall, G., Lundwall, M., . . . Björneholm, O. (2006). Magnetron-based Source of Neutral Metal Vapors for Photoelectron Spectroscopy. Review of Scientific Instruments, 77, 033106
Open this publication in new window or tab >>Magnetron-based Source of Neutral Metal Vapors for Photoelectron Spectroscopy
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2006 (English)In: Review of Scientific Instruments, Vol. 77, p. 033106-Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-83598 (URN)
Available from: 2006-11-07 Created: 2006-11-07 Last updated: 2017-01-25
Lundwall, M., Lindblad, A., Bergersen, H., Rander, T., Öhrwall, G., Tchaplyguine, M., . . . Björneholm, O. (2006). Photon energy dependent intensity variations observed in Auger spectra of free argon clusters. Journal of Physics B: Atomic, Molecular and Optical Physics, 39(16), 3321-3333
Open this publication in new window or tab >>Photon energy dependent intensity variations observed in Auger spectra of free argon clusters
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2006 (English)In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 16, p. 3321-3333Article in journal (Refereed) Published
Abstract [en]

Photon energy dependent intensity variations are experimentally observed in the L2,3M2,3M2,3 Auger spectra of argon clusters. Two cluster sizes are examined in the present study. Extrinsic scattering effects, both elastic and inelastic, involving the photoelectron are discussed and suggested as the explanation of the variations in the Auger signal. The atoms in the first few coordination shells surrounding the core-ionized atom are proposed to be the main targets for the scattering processes.

National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-95325 (URN)10.1088/0953-4075/39/16/015 (DOI)000239774200017 ()
Available from: 2007-01-16 Created: 2007-01-16 Last updated: 2017-12-14Bibliographically approved
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