Soft X-ray spectroscopy and the non-destructive chemical state analysis of thick films and surface layers (10-1000 nm)

Abstract

The use of low-energy electron beams to initiate X-ray spectroscopic analysis of surface layers, 10-1000 nm thick, is described. The probed depth is controlled by the energy of the bombarding electrons in the range 3-12 kV and the characteristic soft X-rays emitted by the sample are analysed by a wavelength dispersive spectrometer [Telsec Betaprobe]. Soft X-rays can exhibit large `chemical shifts'. This property is used to determine the chemical state of elements such as; aluminium in alumina layers on aluminium metal; iron and chromium in oxide layers on steel, and boron in silica layers containing traces of boron and phosphorus.