Adsorption equilibria and kinetics of H2 at nearly ideal (2 x 1)Si(100) inner surfaces

Silicon nanocavities can be terminated with hydrogen by wet chemical etching. Their infrared spectra can to a large extent be interpreted in terms of silicon monohydrides on H(7 x 7)Si(111), H(1 x 1)Si(111) and H (2 x 1)Si(100), and of silicon dihydrides on H(1 x 1)Si(100). The time evolution under isothermal conditions (600 degrees C) of the (1 0 0) faces admits a description in terms of transformation from H(1 x 1)Si(100) into (2 x 1) Si(100) with simultaneous H-2 adsorption onto (2 x 1)Si(100) neat dimers. In so doing the inner H-2 pressure decreases by about one order of magnitude from the initial value of 3 x 10(3) Torr. The unique properties of nanocavities allow their use as nanoreactors: this has led to the determination of the sticking coefficient for H-2 adsorption in conditions of pressure, temperature and adventitious contamination otherwise not achievable. (C) 2010 Elsevier B.V. All rights reserved.