DIRECT INFRARED PHOTODESORPTION OF PHYSISORBED H-2

Blackbody radiation induced desorption rates of H-2 and D-2 physisorbe d on a Cu(510) surface were determined via electron-energy-loss measur ements. Intense dipole-excited vibrational transitions to high-lying b ound levels in the physisorption well indicate the possibility of dire ct infrared photodesorption. We have calculated rates for such a mecha nism from spectroscopic data for H-2 adsorbed on the (100)-like terrac es and find excellent agreement with the experimental results.