Spectroscopy

A method of performing electron spectroscopic surface analysis of a solid material, comprising the steps of directing a primary electron beam from a gun at a surface of a target of said material in a vacuum chamber, said primary electron beam being of energy suitable for the production of Auger electron emission from said target surface, applying an a.c. signal modulated variable retard potential to said target, providing a detector circuit connected to said target, said detector circuit is tuned to measure the second harmionic of the a.c. modulation signal, measuring with said detector circuit a current one separable component of said detector circuit being proportional to the instantaneous net emitted flux of secondary electrons which leave the target as a function of the retard potential, producing with said measured current as a function of the retard potential, an energy spectrum of said secondary electrons characteristic of the target surface and plotting the detector output as a function of the retard potential to produce a spectrum of the first derivative of the secondary electron energy with respect to the retard potential so as to enhance the display of Auger transitions.