VUV photodesorption of molecular hydrogen from the hydrogenated silicon(III) surface

The photochemical desorption of molecular hydrogen was investigated by F-2- laser irradiation (157 nm) of a Si(111)-(1 X 1):H surface. The photon energ y of 7.9 eV used was in the region of the broad sigma-sigma* optical transi tion of SiH centered around 8.5 eV. Molecular-dynamics calculations, based on a Tersoff-type interaction potential between silicon and hydrogen, descr ibe the reaction of a hydrogen atom created in a direct bond-breaking proce ss with a neighboring hydrogen atom to form molecular hydrogen. This second ary surface reaction preserves the non-thermal character of the desorption process. (C) 1999 Elsevier Science B.V. All rights reserved.