Simple Electron Diffraction Camera for the Examination of Alkali Antimonide Photoelectric Films

Abstract

A simple and inexpensive electron diffraction apparatus has been built which can be used for the preparation of photocathodes and the subsequent examination of their patterns under conditions of high vacuum necessary for the preservation of photoelectric sensitivity. The tube consists essentially of an oscilloscope-type envelope with a high voltage display kinescope electron gun assembly and a side arm in which the photoelectric film can be prepared. The sample can then be moved in front of the electron beam, and the resultant electron diffraction pattern is displayed on a phosphor screen. Up to five cathodes can be prepared and examined separately in the same tube. Several sensitive photocathodes have been prepared and their diffraction patterns examined. The technique has been particularly useful for following the formation of multialkali cathodes of the type Na2KSb from the deposition of the initial antimony layer to the final sensitive photocathode surface.