High-brightness photocathodes through ultrathin surface layers on metals.
We report how ultrathin MgO films on Ag(001) surfaces can be used to control the emittance properties of photocathodes. In addition to substantially reducing the work function of the metal surface, the MgO layers also favorably influence the shape of the surface bands resulting in the generation of high-brightness electron beams. As the number of MgO surface layers varies from 0 to 3, the emitted electron beam becomes gradually brighter, reducing its transverse emittance to 0.06 mm mrad. We suggest the use of such photocathodes for the development of free-electron x-ray lasers and energy-recovery linac x-ray sources.
Németh
Károly
K
Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA. Nemeth@ANL.Gov
Harkay
Katherine C
KC
van Veenendaal
Michel
M
Spentzouris
Linda
L
White
Marion
M
Attenkofer
Klaus
K
Srajer
George
G