| AVS 62nd International Symposium & Exhibition | |
| Surface Science | Tuesday Sessions |
| Session SS+AS+EN+NS-TuM |
| Session: | Nanostructures, Nanoplasmonics and Surface Reactions |
| Presenter: | Zejun Ding, University of Science and Technology of China |
| Authors: | H. Xu, University of Science and Technology of China B. Da, University of Science and Technology of China S.F. Mao, University of Science and Technology of China J. Toth, Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI) K. Tokesi, Institute for Nuclear Research, Hungarian Academy of Sciences (ATOMKI) Z.J. Ding, University of Science and Technology of China |
| Correspondent: | Click to Email |
The energy loss function (ELF), which is directly related to optical constants of a solid, dominates the energy loss process of an electron moving inside or flying nearby a solid. It is therefore able to obtain optical constants by surface electron spectroscopy technique. Accurate measurement of optical data by optical methods in a photon energy range up to 102 eV is still insufficient; delicate experimental conditions are required when measuring data in vacuum ultraviolet region (20-50 eV). Fortunately, such information is essentially contained in and, therefore, can be extracted from a reflection electron energy loss spectroscopy (REELS) spectrum due to the shorter information depth of signal electrons compared with that of photons.
In the present work, reflection electron energy loss spectra of transition metals, Fe, Ni and Pd, were measured at several primary energies ranging from 0.5 keV up to 5 keV and in a wide energy-loss range. Prior to the measurements in situ cleaning of the sample surface was performed using Ar+ ion sputtering with proper current density and time. Vacuum was kept as 1.5×10−9 mbar in the measurement chamber during the REELS measurements. Surface cleanness was checked by XPS in several cases after the REELS measurements. An improved reverse Monte Carlo simulation for determination of optical constants via accurate description of electron inelastic transport process was performed. ELF of those metals were extracted from experimental REELS spectra. The accuracy of the obtained optical data has been confirmed by f-sum and ps-sum rules. Comparisions of our data with other sources from either experimental measurements or density functional theory calculation are given.