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Deeper Insight into Depth-Profiling of Aqueous Solutions Using Photoelectron Spectroscopy

Bjorneholm, Olle; Werner, Josephina; Ottosson, Niklas; Öhrwall, Gunnar LU ; Ekholm, Victor; Winter, Bernd; Unger, Isaak and Soderstrom, Johan (2014) In Journal of Physical Chemistry C 118(50). p.29333-29339
Abstract
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... (More)
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, approximate to 100 eV, which lies in the range of pronounced intensity oscillations. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physical Chemistry C
volume
118
issue
50
pages
29333 - 29339
publisher
The American Chemical Society
external identifiers
  • wos:000346759300046
  • scopus:84918813399
ISSN
1932-7447
DOI
10.1021/jp505569c
language
English
LU publication?
yes
id
f57c46fc-43ee-4a46-8eea-173cdd7c0602 (old id 5194686)
date added to LUP
2015-03-27 12:08:40
date last changed
2017-09-03 03:02:51
@article{f57c46fc-43ee-4a46-8eea-173cdd7c0602,
  abstract     = {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, approximate to 100 eV, which lies in the range of pronounced intensity oscillations.},
  author       = {Bjorneholm, Olle and Werner, Josephina and Ottosson, Niklas and Öhrwall, Gunnar and Ekholm, Victor and Winter, Bernd and Unger, Isaak and Soderstrom, Johan},
  issn         = {1932-7447},
  language     = {eng},
  number       = {50},
  pages        = {29333--29339},
  publisher    = {The American Chemical Society},
  series       = {Journal of Physical Chemistry C},
  title        = {Deeper Insight into Depth-Profiling of Aqueous Solutions Using Photoelectron Spectroscopy},
  url          = {http://dx.doi.org/10.1021/jp505569c},
  volume       = {118},
  year         = {2014},
}