Journal
JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA
Volume 177, Issue 2-3, Pages 60-70Publisher
ELSEVIER
DOI: 10.1016/j.elspec.2009.08.007
Keywords
Liquid water and aqueous solutions; X-ray photoelectron spectroscopy; Solution interfacial structure; Electron inelastic mean free path; Electron attenuation lengths in water; Molecular dynamics
Categories
Funding
- Czech Ministry of Education [LC512]
- NSF (National Science Foundation) [CHE 0431312, CHE 0617060]
- Max-Born-Institut
- Deutsche Forschungsgemeinschaft [WI 1327/3-1]
Ask authors/readers for more resources
Photoelectron (PE) spectroscopy measurements from liquid water and from a 4m NaI aqueous solution are performed using a liquid microjet in combination with soft X-ray synchrotron radiation. From the oxygen is PE signal intensity from liquid water, measured as a function of photon energy (up to 1500 eV), we quantitatively determine relative electron inelastic effective attenuation lengths (EAL) for (photo)electron kinetic energies in the 70-900 eV range. In order to determine the absolute electron escape depths a calibration point is needed, which is not directly accessible by experiment. This information can instead be indirectly derived by comparing PE experiments and molecular dynamics (MD) simulations of an aqueous solution interface where density profiles of water, anions, and cations are distinctively different. We have chosen sodium iodide in water because iodide has a considerable propensity for the solution surface, whereas the sodium cation is repelled from the surface. By measuring the intensities of photoelectrons emitted from different orbitals of different symmetries from each aqueous ion we also evaluate whether gas-phase ionization cross sections and asymmetry parameters can describe the photoemission from ions at and near the aqueous solution/vapor interface. We show that gas-phase data reproduce surprisingly well the experimental observations for hydrated ions as long as the photon energy is sufficiently far above the ionization threshold. Electrons detected at the higher photon energies originate predominantly from deeper layers, suggesting that bulk-solution electron elastic scattering is relatively weak. (C) 2009 Published by Elsevier B.V.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available