Generation of hot charge carriers by adsorption of hydrogen and deuterium atoms on a silver surface

Abstract

The generation of hot charge carriers during adsorption of atomic hydrogen and atomic deuterium on Ag has been investigated by chemicurrent measurements using thin-metal film $\mathrm{Ag}∕p\text{\ensuremath{-}}\mathrm{Si}(111)$ Schottky diodes. The detected currents are due to nonadiabatic dissipation of chemical energy and exhibit a strong isotope effect. The chemicurrent efficiency is found to be 3.6 times larger for atomic hydrogen adsorption than atomic deuterium. The isotope effect does not depend on the metal film thickness of the device. The results are in excellent agreement with the electronic friction model of chemicurrents [Phys. Rev. Lett. 88, 166802 (2002)] and give a temperature parameter of $1690\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ for the Boltzmann-type energy distribution of the hot charge carriers excited by atomic hydrogen adsorption on Ag.