PHOTON-STIMULATED DESORPTION FROM COLD SURFACES

THE SUCCESSFUL OPERATION OF THE SUPERCONDUCTING SUPER COLLIDER REQUIRES MINIMIZING THE EFFECTS OF PHOTO-STIMULATED DESORPTION (PSD) OF H2, CO, CO2, AND OTHER GASES FROM THE BEAM LINE THAT IS EXPOSED TO HIGH FLUXES OF SYNCHROTRON RADIATION. THIS PROJECT ESTABLISHES THE METHODOLOGY FOR A BETTER UNDERSTANDING OF THE FUNDAMENTAL PHYSICS INVOLVED IN THE PSD PROCESS AT ROOM AND LIQUID NITROGEN TEMPERATURES, USING PHOTONS FROM CONVENTIONAL LASERS WITH WELL-KNOWN ENERGY-UP-AND-DOWN-CONVERSION TECHNIQUES. PHASE I INVESTIGATES PHOTO-DESORPTION OF H2, CO, AND CO2 FROM STAINLESS STEEL (SS) AND COPPER-COATED SS. THE PHOTON SOURCES CONSIST OF PULSED TUNABLE DYE LASERS EMPLOYING UP (WAVE-MIXING) OR DOWN (STIMULATED ELECTRONIC RAMAN SCATTERING (SERS)) CONVERSION TECHNIQUES. THE ATOMIC AND MOLECULAR SPECIES ARE BEING VELOCITY (ENERGY) ANALYZED BY TIME-OF-FLIGHT FOLLOWED BY MASS ANALYSIS WITH A SECOND TIME-OF-FLIGHT MASS SPECTROMETER. THE METHOD PROVIDES QUANTITATIVE MEASUREMENTS OF ATOMIC AND MOLECULAR (E.G., H, H2) YIELD AS WELL AS THEIR KINETIC ENERGY DISTRIBUTIONS. EXPERIMENTS ARE BEING CONDUCTED TO OBSERVE THE DIFFERENCE BETWEEN PSD AT ROOM TEMPERATURE AND PSD AT LIQUID NITROGEN TEMPERATURE.