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 permeation method usually used, this allows the surface temperature to be controlled over a considerable range and is not limited to high temperatures. We have detected the desorbing molecules in a quantum state specific manner using (2+1) REMPI with a sensitivity of 5 x 10(-12) mbar per quantum state. Rotational populations were obtained by calibrating against a Knudsen source and can be approximately described by a Boltzmann distribution with a temperature of 550 K for desorption from a 210 K surface. Increasing surface temperature caused a decrease in the rotational temperature of the desorbing gas.