AVS 63rd International Symposium & Exhibition
    In-Situ and Operando Spectroscopy and Microscopy for Catalysts, Surfaces, & Materials Focus Topic Thursday Sessions
       Session IS-ThA

Paper IS-ThA8
Calculations of Electron Inelastic Mean Free Paths for Liquid Water at Energies from 50 eV to 30 keV

Thursday, November 10, 2016, 4:40 pm, Room 101C

Session: Ambient Pressure Photoelectron Spectroscopy and Scanning Probe Techniques
Presenter: Cedric Powell, National Institute of Standards and Technology
Authors: H. Shinotsuka, National Institute for Materials Science (NIMS), Japan
B. Da, National Institute for Materials Science (NIMS), Japan
S. Tanuma, National Institute for Materials Science (NIMS), Japan
H. Yoshikawa, National Institute for Materials Science (NIMS), Japan
C.J. Powell, National Institute of Standards and Technology
DR. Penn, National Institute of Standards and Technology
Correspondent: Click to Email
We calculated electron inelastic mean free paths (IMFPs) for liquid water from its optical energy-loss function (ELF) for electron energies from 50 eV to 30 keV. These calculations were made with the relativistic full Penn algorithm (FPA) that has been used for previous IMFP and electron stopping-power calculations for many elemental solids [1]. We also calculated IMFPs of water with three additional algorithms: the relativistic single-pole approximation (SPA), the relativistic simplified SPA, and the relativistic extended Mermin method. These calculations were made using the same optical ELF in order to assess any differences of the IMFPs arising from choice of the algorithm. We found good agreement among the IMFPs from the four algorithms for energies over 300 eV. For energies less than 100 eV, however, large differences became apparent. IMFPs from the relativistic TPP-2M equation for predicting IMFPs were in good agreement with IMFPs from the four algorithms for energies between 300 eV and 30 keV but there was poorer agreement for lower energies. We made comparisons of our IMFPs with earlier calculations from authors who had used different algorithms and different ELF data sets. IMFP differences could then be analyzed in terms of the algorithms and the data sets. Finally, we compared our IMFPs with measurements of IMFPs and of a related quantity, the effective attenuation length (EAL). There were large variations in the measured IMFPs and EALs (as well as their dependence on electron energy). Further measurements are therefore required to establish consistent data sets and for more detailed comparisons with calculated IMFPs.

[1] H. Shinotsuka, S. Tanuma, C. J. Powell, and D. R. Penn, Surf. Interface Anal. 47, 871 (2015).