Low energy electron desorption of mixed adsorbates

Abstract

When hydrogen adsorbs on a polycrystalline nickel foil, the current of H + ions desorbed by a beam of low energy (100 V) electrons increases monotonically with hydrogen uptake. In the presence of co-adsorbed carbon monoxide the total desorption cross section is greatly increased and there is no longer a monotonic relationship between uptake and H + ion current. Partial pressures of carbon monoxide as low as 2 × 10 −9 torr can produce a noticeable and, at present, unexplainable effect on the desorbed hydrogen ion signal and therefore the utmost rigor in vacuum technique is required for reliable electron desorption experiments.