Molecular desorption of a nonevaporable getter St 707 irradiated at room temperature with synchrotron radiation of 194 eV critical photon energy

Abstract

Photon stimulated molecular desorption from a nonevaporable getter (NEG) St 707® (SAES Getters™) surface after conditioning and after saturation with isotopic carbon monoxide [cf. nomenclature in Handbook of Chemistry and Physics, 74th edition, edited by D. R. Lide (CRC Press, Boca Raton, 1994)] C13O18, has been studied on a dedicated beamline at the EPA ring at CERN. The synchrotron radiation of 194 eV critical energy and with an average photon intensity of ∼1×1017 photons s−1 was impinging on the sample at perpendicular incidence. It is found that the desorption yields η (molecules/photon) of the characteristic gases in an UHV system (hydrogen, methane, carbon monoxide, and carbon dioxide) for a freshly activated NEG and for a NEG fully saturated with C13O18 are lower than that of 300 °C baked stainless steel.