Only 5 or 6 years ago electron spectroscopy for chemical applications (ESCA) was a comparatively unknown technique being explored only by workers with the courage and technical expertise necessary to build their own spectrometers [1, 2]. However, the published work of these pioneers in the field indicated the enormous potential of the technique and within a space of 3 years or so at least ten instrument manufacturers were advertising their wares. The availability of instruments was rapidly capitalized on by the scientific community, and a review of the field for the period 1968 to 1971 [3] included 166 references. Since that data, publications relating to ESCA have continued to proliferate and the technique has proved valuable across a wide range of investigations.