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Instrumental effects in the analysis of non‐homogeneous specimens in XPS
Author(s) -
Koening M. F.,
Grant J. T.
Publication year - 1988
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.740110619
Subject(s) - kinetic energy , x ray photoelectron spectroscopy , homogeneity (statistics) , spectrometer , homogeneous , spectral line , intensity (physics) , analytical chemistry (journal) , materials science , x ray , optics , chemistry , physics , nuclear magnetic resonance , statistics , mathematics , quantum mechanics , astronomy , chromatography , thermodynamics
The effects of specimen non‐homogeneity on XPS spectra have been studied for a Kratos ES300 x‐ray photoelectron spectrometer. This instrument was equipped with a real‐time imaging system to permit accurate specimen positioning. It was found that, for a correctly positioned specimen, both the measured kinetic energy and intensity of a photoelectron peak depended on the position on the specimen from which the signal arose. The variation in measured kinetic energy across the width of the entrance slit was found to be ∼1.7 eV for the widest entrance slit and highest pass energy of our spectrometer (FAT mode, 130 eV pass energy, 5 mm wide slit). The intensity of the photoelectron peaks was found to vary by a factor of ∼2 across the analyzer acceptance area for the widest (5 mm) slit, which corresponds to the inverse square of the distance from the X‐ray source. These studies show that significant shifts in kinetic energy are possible due solely to specimen non‐homogeneity (as opposed to chemical shifts) as well as misleading intensity variations. Therfore, data obtained from non‐homogeneous specimens should be carefully examined for these artifacts when using large‐ area XPS analysis.