Photoemission from K–Te photocathodes

Abstract

In this letter the photoemissive properties of K–Te films produced under ultrahigh vacuum conditions are reported. K–Te photocathodes were fabricated by vapor deposition of Te and K onto a Mo substrate into the preparation chamber of the Free Electron Laser of the University of Twente. The highest quantum efficiency obtained at 259 nm was 11.1%, measured just after evaporation; this value decreased in a few minutes to a stable quantum efficiency of 8.3%. The reported results show that K–Te can be considered a promising material for the use as a photocathode in photoinjectors.