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

Unified description of H-atom–induced chemicurrents and inelastic scattering

“…This analysis is consistent with previous work suggesting that only the H-H recombination reaction on Au produces hot electrons (24) and chemicurrent (13). We also note that the H-adsorption-induced chemicurrents seen by Schottky diode experiments on Ag surfaces (7,11) were performed at a surface temperature (100-135 K) far lower than the H 2 recombinative desorption temperature (∼170 K) (25). Thus, there was no chance that this source of hot electrons could have been seen in those experiments.…”

“…3 (Upper), the gray vertical line at 0.5 eV marks the Schottky barrier for Ag on n-doped silicon--the theoretically predicted isotope effect (3.7) is in excellent agreement with experiment (black star in the figure). Remarkably, the theoretically predicted absolute magnitude of the chemicurrent (0.0036 e/H) is in good agreement with experiment (∼0.01 e/H) (9)(10)(11). This suggests that barrier crossing losses in these devices are small, in good agreement with conclusions from ref.…”

“…However, a growing number of examples have been found where electronic and nuclear degrees of freedom are strongly coupled in violation of the BOA (2-6). H-atom interactions at metals offer a remarkable opportunity to test non-BOA theories against experiment, since H-adsorptioninduced chemicurrent experiments (7)(8)(9)(10)(11)(12)(13)(14) offer a direct measure of electronic excitation and H-atom inelastic scattering experiments (15) directly probe nuclear motion. In chemicurrent experiments, exothermic H interactions like adsorption and recombination produce hot electrons that pass over a potential barrier to be collected.…”

“…Hence, the magnitude of the chemicurrent is dependent on both the reaction-induced production of hot electrons and the likelihood of transmission over the barrier. To reduce uncertainties associated with barrier transmission, the ratio of hydrogen-and deuterium-induced chemicurrent is often measured--H-induced chemicurrents are typically two to five times larger than those from D atoms (7,(11)(12)(13). H-atom surface scattering experiments yield H-atom translational energy loss distributions.…”

Vibrational deexcitation and rotational excitation of H2 and D2 scattered from Cu(111): Adiabatic versus non-adiabatic dynamics

“…Experiments developed during the last few years have measured, for example, chemicurrents and creation of hot electrons during the chemisorption of atoms and molecules on metal films and surfaces, [1][2][3][4][5] highly efficient multi-quantum vibrational relaxation of highly vibrationally excited NO molecules scattered from metal surfaces, 6,7 and even electron emission upon scattering of highly vibrationally excited NO from a low work function metal surface. 8 Nevertheless, the fundamental question to be answered now is: how much does the presence of electronic excitations influence the interactions between molecules and metal surfaces?…”