Surface studies by grazing‐exit electron probe microanalysis (GE‐EPMA)

Abstract

AbstractSurface analysis was performed by a new analytical method, grazing‐exit electron probe microanalysis (GE‐EPMA). At grazing‐exit (small x‐ray take‐off) angles, only characteristic x‐rays emitted from the near‐surface regions are measured because of strong absorption and refraction effects at the surface. The exit angle was carefully determined using a stepping motor (with a minimum step angle of 0.018°), and the emergent x‐rays were measured by an energy‐dispersive x‐ray detector and analyzed with a multi‐channel analyzer (MCA). A computer controlled both the stepping motor and the MCA so that the exit‐angle dependence of the characteristic x‐ray intensities was measured automatically. The angle‐dependent curve for a thin cobalt film (5 nm thick) deposited on a silicon wafer indicated that the cobalt x‐rays predominated at grazing exit angles, demonstrating that high surface sensitivity was obtainable under these conditions. The results from a polished stainless‐steel sample revealed chromium enrichment at grazing exit angles, which corresponds to a thin passivation layer of chromium oxide at the surface. Both sets of data suggest that GE‐EPMA is a promising technique for localized surface analysis. Copyright © 2001 John Wiley & Sons, Ltd.