Photon Stimulated Desorption(PSD) was measured from a copper beam chamber after completely removing the vacuum surface oxide in order to reduce the PSD. Measurements of PSD and reflected specular photons were performed on NSLS beamline U9a at Brookhaven National Laboratory. PSD causes a pressure rise in accelerator and storage ring vacuum which limits their performance. For this experiment, a KEKB factory beam chamber from a previous experiment was chemically etched and chemically cleaned prior to installation on beamline U9a. Previous PSD measurements have shown that this chemical treatment removes any memory of prior exposure or conditioning. After installation, the copper chamber and end stop were vacuum baked to 250 °C for more than a week to completely remove vacuum surface oxides. The chamber was exposed to more than 1x10@super 23@ photons direct from the source having a critical energy of 595 eV and striking at an incident angle of 100 mrad. The major PSD yields for hydrogen, carbon monoxide, carbon dioxide, methane, and water are reported as a function of accumulated photon flux and preparation. The PSD yields for the copper chamber, after oxide removal, were found to be greatly reduced when compared to previous measurments at this laboratory and by those reported from other laboratories. @FootnoteText@ @footnote 1@Work performed under the auspices of the U.S. Department of Energy, under contract DE-AC02-98CH10886.