Incorporation of positively and negatively polarized hydrogen and deuterium adspecies from the surface into the bulk of thin palladium films

The incorporation of hydrogen and deuterium adspecies from the surface of a thin palladium film into the bulk has been studied measuring simultaneously the surface potential changes by means of high sensitivity (± 1 mV), short response time (0.1 s) static capacitor system, and pressure by means of the ultrasensitive Pirani type gauge. It has been found that the positively polarized β+ adspecies of hydrogen incorporate quickly at 78 K and 87 K. via a tunneling mechanism, with a diffusion coefficient of 3 × 10−13 cm2s. The β+ adspecies of deuterium incorporate with slightly increasing diffusion coefficient with the temperature increase: 1 × 10−13 cm2s at 78 K and 2 × 10−13 cm2s at 87 K. The negatively polarized adspecies β−, which strongly predominate and at 160 K, slowly incorporate in the bulk of palladium.