INTERNAL STATE DISTRIBUTIONS FOR D-2 RECOMBINATIVE DESORPTION FROM AG(111)

We have studied the recombinative desorption of D-2 from Ag(111) using an atomic beam source to deposit D atoms. In contrast to the permeati on method usually used, this allows the surface temperature to be cont rolled over a considerable range and is not limited to high temperatur es. We have detected the desorbing molecules in a quantum state specif ic manner using (2+1) REMPI with a sensitivity of 5 x 10(-12) mbar per quantum state. Rotational populations were obtained by calibrating ag ainst a Knudsen source and can be approximately described by a Boltzma nn distribution with a temperature of 550 K for desorption from a 210 K surface. Increasing surface temperature caused a decrease in the rot ational temperature of the desorbing gas.