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Method for resurrecting negative electron affinity photocathodes after exposure to an oxidizing gas

United States Patent

October 30, 2012
View the Complete Patent at the US Patent & Trademark Office
A method by which negative electron affinity photocathodes (201), single crystal, amorphous, or otherwise ordered, can be made to recover their quantum yield following exposure to an oxidizing gas has been discovered. Conventional recovery methods employ the use of cesium as a positive acting agent (104). In the improved recovery method, an electron beam (205), sufficiently energetic to generate a secondary electron cloud (207), is applied to the photocathode in need of recovery. The energetic beam, through the high secondary electron yield of the negative electron affinity surface (203), creates sufficient numbers of low energy electrons which act on the reduced-yield surface so as to negate the effects of absorbed oxidizing atoms thereby recovering the quantum yield to a pre-decay value.
Mulhollan; Gregory A. (Austin, TX), Bierman; John C. (Austin, TX)
12/ 931,839
February 11, 2011
FEDERALLY SPONSORED RESERCH This work was supported by the Department of Energy SBIR under Grant No. DE-SC0002268.