Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 58: Poster Session III (Solid/liquid interfaces; Metals; Semiconductors; Oxides and insulators)
O 58.12: Poster
Wednesday, March 28, 2012, 18:15–21:45, Poster B
Investigation of the laser-cleaning process on Lead photocathodes — •Susanne Schubert1, Roman Barday1, Thorsten Kamps1, John Smedley2, Robert Nietubyc3, Andrei Varykhalov1, and Giesela Weinberg4 — 1HZB, Berlin, Germany — 2BNL, Upton, USA — 3NCBJ, Swierk, Poland — 4FHI, Berlin, Germany
Metal photocathodes are widely used in electron injectors due to their stability and long life time. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley [1]. We present the results of a combined photo emission, SEM and quantum efficiency measurement study on witness samples. Thin Lead films were arc-deposited on optical polished Mo-substrates [2]. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM.
[1]J. Smedley et al, PRST-AB 11, 013502 (2008) [2]Rao, T. et al., IPAC 2010, THPEC020 (2010)