TY - JOUR
T1 - High-energy electron scattering from TiO2 surfaces
AU - Vos, M.
AU - Grande, P. L.
N1 - Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2015/7/1
Y1 - 2015/7/1
N2 - Electron scattering experiments at keV energies from a TiO2 surface are presented. The paper aims to give an overview of the wide variety of information that can be extracted from such experiments. If the elastic scattering cross sections are known these experiments give the sample composition, if the composition is known one can extract the ratio of the elastic cross sections. In the experiments described here the ratio of the Ti and O cross sections deviates noticeably from the one calculated from the Rutherford formula. The peak widths give access to the mean kinetic energies of the atoms present. We show that the mean kinetic energy of Ti atoms is less than that of O atoms, but both kinetic energies are still affected by quantum effects, i.e. are larger than 3/2kT. We extract an estimate of the dielectric function of TiO2 by extending the measurement up to 100 eV energy loss. At these high energies the determination of the dielectric function from the measured energy loss spectrum is relatively simple, as the contribution of surface excitations is small and the obtained loss function is closely related to the dielectric function in the optical limit. Finally, we use the technique to monitor the surface after sputtering with Ar+ ions, and observe both differences in composition and electronic structure induced by sputtering that disappear again after annealing.
AB - Electron scattering experiments at keV energies from a TiO2 surface are presented. The paper aims to give an overview of the wide variety of information that can be extracted from such experiments. If the elastic scattering cross sections are known these experiments give the sample composition, if the composition is known one can extract the ratio of the elastic cross sections. In the experiments described here the ratio of the Ti and O cross sections deviates noticeably from the one calculated from the Rutherford formula. The peak widths give access to the mean kinetic energies of the atoms present. We show that the mean kinetic energy of Ti atoms is less than that of O atoms, but both kinetic energies are still affected by quantum effects, i.e. are larger than 3/2kT. We extract an estimate of the dielectric function of TiO2 by extending the measurement up to 100 eV energy loss. At these high energies the determination of the dielectric function from the measured energy loss spectrum is relatively simple, as the contribution of surface excitations is small and the obtained loss function is closely related to the dielectric function in the optical limit. Finally, we use the technique to monitor the surface after sputtering with Ar+ ions, and observe both differences in composition and electronic structure induced by sputtering that disappear again after annealing.
KW - Dielectric function
KW - Elastic cross sections
KW - Electron
KW - Preferential sputtering
KW - Rutherford backscattering
KW - TiO
UR - http://www.scopus.com/inward/record.url?scp=84939963963&partnerID=8YFLogxK
U2 - 10.1016/j.nimb.2014.11.083
DO - 10.1016/j.nimb.2014.11.083
M3 - Article
SN - 0168-583X
VL - 354
SP - 332
EP - 339
JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
ER -