SIMPLE SOURCE OF ATOMIC-HYDROGEN FOR ULTRAHIGH-VACUUM APPLICATIONS

A simple doser for atomic hydrogen is described. It basically consists of a tungsten capillary which on the outlet is heated by electron bombardment to 1800-2000 K. This temperature is sufficient to achieve nearly total H-2 dissociation under relevant working pressures. The performance of the atomic hydrogen source was tested by H adsorption studies on Cu(110). The saturation coverage on this surface could be achieved with a nominal exposure which was smaller by a factor of approximately 10(-3) as compared to conventional methods of dissociation on a hot filament. The higher efficiency of the present H source greatly reduces the risk of sample contamination.