Photon stimulated desorption from aluminum and electroplated vacuum chambers have been obtained using synchrotron radiation of critical energies ranging from 12.4 to 280 eV. The authors first compared different cleaning methods on electroplated copper, including bakeout, prebakeout (bakeout in situ, venting, and pumping) and glow discharge with argon and 10% oxygen. As expected in situ bakeout gave the best results, followed by glow discharge, which was quite effective in removing desorbed gases. After this experiment, the authors compared two different copper electroplating methods, Fluhmann and CERN workshop electroplated copper, giving results with factors from I to 3 for initial yields. During dose accumulation, the cleaning effect was more clearly seen in CERN plated copper than in Fluhmann plated copper, specially for hydrogen. After this dose accumulation and with no beam circulating, gas desorption yields were found to decrease quickly except that of water, which decreased slowly, suggesting a process where water is formed on the surface and subsequently desorbed. Initial desorption yields were also measured for an aluminum chamber, before and after bakeout. The authors obtained that initial yields are almost linear with critical energy in this range. The difference between baked and unbaked aluminum is mainly due to water yield which is greatly reduced by the baking procedure. (c) 2007 American Vacuum Society.