title: High-brightness photocathodes through ultrathin surface layers on metals.
abstract: 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.
authors.affiliation: Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA. Nemeth@ANL.Gov
authors.forename: Károly
authors.initials: K
authors.lastname: Németh
authors.forename: Katherine C
authors.initials: KC
authors.lastname: Harkay
authors.forename: Michel
authors.initials: M
authors.lastname: van Veenendaal
authors.forename: Linda
authors.initials: L
authors.lastname: Spentzouris
authors.forename: Marion
authors.initials: M
authors.lastname: White
authors.forename: Klaus
authors.initials: K
authors.lastname: Attenkofer
authors.forename: George
authors.initials: G
authors.lastname: Srajer