VIBRATIONAL EFFECTS IN THE ASSOCIATIVE DESORPTION OF H-2

Experimental observations and a theory of vibrational excitation in associative desorption are examined. Time-dependent quantum calculations on a barrierless potential demonstrate the importance of contributions from excited vibrational states of the adsorbed H atoms. In addition, their inclusion is a necessary condition for time reversal symmetry (microscopic reversibility) to hold. Attempts to simulate the experimental results with model forms of the sticking function indicate that there is no unique route between data and potential energy surfaces.