Changes in shape and position of long-wavelength X-ray lines measured by wavelength dispersive spectrometry (WDS) reflect changes in the density of bonding states of the emitting atom. However, some features of soft X-ray spectra are not due to bonding. For example, small peaks on the shorter-wavelength side of a characteristic peak probably arise from double ionization, absorption effects must be considered and there may be artefacts from the diffracting crystal itself. Nonetheless, when there are dramatic shape changes, spectrometry of soft X-rays can usefully augment microanalysis particularly in the study of tiny particulates which may be difficult to prepare for transmission microscopy.5 Two examples of spectrometry of O Kα follow.

Oxidation of very fine TiB2 particulates is a problem in the ceramics industry. The backscattered electron (BSE) micrograph in fig. 1 shows a particle section with a central core of TiB2 and a darker, oxidised rim analysing roughly like a borate, interspersed with brighter regions, probably TiO2.