COUPLING OF VIBRATIONAL AND TRANSLATIONAL ENERGY IN THE ADSORPTION OF H2 ON FE(100) - STATE-RESOLVED STICKING COEFFICIENTS

The system II2/Fc(100) has been investigated with respect to vibrational contributions to the adsorption dynamics. In the low energy regime both H2 and D2 adsorb predominantly in the state nu = 0. This leads to a sizeable isotopic effect in favor of II2. At higher energies, and higher temperatures, the contributions of the states nu = 1 reverse the isotope effect. It has been possible to obtain state resolved sticking coefficients for the state nu = 1 and nu = 0 for II2/Fe(100) and D2/Fe(100) as well as for H2/Cu(110). At translational energies above 0.16 eV hydrogen molecules in the state nu - 1 have an adsorption probability of unity on Fe(100). Sticking coefficients for hydrogen in the state nu - 1 are one to two orders of magnitude larger than for nu = 0.