Open AccessSurface EXAFS via differential electron yield
Author(s) -
Isomura Noritake,
Murai Takaaki,
Nomoto Toyokazu,
Kimoto Yasuji
Publication year - 2017
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577516019676
Subject(s) - extended x ray absorption fine structure , xanes , auger electron spectroscopy , surface extended x ray absorption fine structure , absorption (acoustics) , materials science , spectroscopy , analytical chemistry (journal) , absorption spectroscopy , electron , chemistry , optics , physics , chromatography , quantum mechanics , nuclear physics , composite material
Surface‐sensitive analysis via extended X‐ray absorption fine‐structure (EXAFS) spectroscopy is demonstrated using a thickness‐defined SiO 2 (12.4 nm)/Si sample. The proposed method exploits the differential electron yield (DEY) method wherein Auger electrons escaping from a sample surface are detected by an electron analyzer. The DEY method removes local intensity changes in the EXAFS spectra caused by photoelectrons crossing the Auger peak during X‐ray energy sweeps, enabling EXAFS analysis through Fourier transformation of wide‐energy‐range spectral oscillations. The Si K ‐edge DEY X‐ray absorption near‐edge structure (XANES) spectrum appears to comprise high amounts of SiO 2 and low Si content, suggesting an analysis depth, as expressed using the inelastic mean free path of electrons in general electron spectroscopy, of approximately 4.2 nm. The first nearest neighbor (Si—O) distance derived from the Fourier transform of the Si K ‐edge DEY‐EXAFS oscillation is 1.63 Å. This value is within the reported values of bulk SiO 2 , showing that DEY can be used to detect a surface layer of 12.4 nm thickness with an analysis depth of approximately 4.2 nm and enable `surface EXAFS' analysis using Fourier transformation.