Escape peaks and internal fluorescence for a Si(Li) detector and general geometry

Abstract

Extends the discussion of escape peaks and internal silicon fluorescence presented by Reed and Ware (see ibid., vol.5, no.6, p.582 (1972)) to the case where the surface of the lithium-drifted silicon detector is not normal to the direction of the incident X-rays. This oblique geometry is used in several SEM and microprobe instruments. It is found that the effect on the escape peak of a change in geometry is not trivial. An equation is derived for the size of the SiK alpha internal fluorescence peak as a function of the X-ray angle of incidence. It is noted, however, that contamination from silicon-containing vacuum oils or greases may obscure the contribution from internal fluorescence.