Scanning Auger and work-function measurements applied to dispenser cathodes

A method to perform spatially resolved work-function measurements has been developed using a modified scanning Auger microprobe (SAM). The basis of the method is that patches of different work function give rise to different onsets of secondary electron emission. The combined SAM-work function measurement method permits a microscopic correlation of emissive or surface dipole properties with elemental composition. The system permits a surface spatial resolution of 0.2 micrometer provided by the focused incident electron beam, and a work-function resolution of better than 0.05 eV. Results are presented for elemental samples, which were used as a test of the work-function mapping ability. Some initial results on dispenser cathode surfaces are also presented.