Development of a New Nonevaporable Getter Coating Using Oxygen-Free Palladium/Titanium, Surface Analysis by Synchrotron Radiation X-ray Photoelectron Spectroscopy, Residual Gas Analysis, and Evaluation of Pumping Speeds

Abstract

We have developed a novel nonevaporable getter named oxygen-free Pd/Ti. After activation at 133℃, oxygen-free Pd/Ti evacuates H2 and CO. Its pumping speeds do not decrease even after repeated cycles of activation and exposure to the air. Surface analysis by synchrotron radiation X-ray photoelectron spectroscopy showed that the carbon contamination decreased to an extent on heating in UHV, but decreased considerably on heating under an O2 pressure. The partial pressures of H2, CO, H2O, and CH4 in an oxygen-free-Pd/Ti coated chamber reduced to some degree after baking in UHV, but reduced remarkably after baking under an O2 pressure (O2 baking). Catalytic chemical reactions which remove carbon and hydrogen adsorbed on Pd surfaces appear to be responsible for the reduction of the partial pressures of H2, CO, H2O, and CH4. The pumping speeds of the oxygen-free Pd/Ti coated chamber for H2 and CO improved remarkably after O2 baking.