Abstract

Laser photons can interact with a gas-solid system to promote heterogenous reactions and to stimulate desorption. Two classes of photon-enhanced surface processes have been extensively investigated in recent years. The first one involves laser-induced adsorbate-surface reaction and desorption resulting in the chemical etching of the solid. The examples include the halogen reactions with silicon and metals affected by ultraviolet and visible photons. Recent time-resolved mass spectrometric studies in conjunction with ESCA, Auger spectroscopy and thermal desorption measurements have revealed interesting surface reaction dynamics and etching mechanisms. The second one involves infrared laser photodesorption initiated by excitation of internal molecular vibrations. Recent studies of the desorption phenomenon for molecules adsorbed on both dielectric and metal surfaces excited by the infrared radiation will be discussed. The photo-excitation process, including both single and multiple photon absorption and the various vibrational energy transfer and relaxation processes related to photodesorption, will be examined with particular emphasis on assessing the quantum and thermally-assisted effects. A review on both classes of laser-stimulated surface processes will be given.

© 1985 Optical Society of America