PHOTOEMISSION FROM K-TE PHOTOCATHODES

In this letter the photoemissive properties of K-Te films produced und er ultrahigh vacuum conditions are reported. K-Te photocathodes were f abricated by vapor deposition of Te and K onto a Mo substrate into the preparation chamber of the Free Electron Laser of the University of T wente. The highest quantum efficiency obtained at 259 nm was 11.1%, me asured just after evaporation; this value decreased in a few minutes t o a stable quantum efficiency of 8.3%. The reported results show that K-Te can be considered a promising material for the use asa photocatho de in photoinjectors. (C) 1996 American Institute of Physics.