ADSORPTION-KINETICS OF CHEMISORPTION BY SURFACE ABSTRACTION AND DISSOCIATIVE ADSORPTION

The kinetics of diatomic molecules adsorbing onto single-crystal surfa ces is considered when this process can occur by a combination of diss ociative adsorption and surface abstraction. The latter process adsorb s one atom on the surface and scatters the other from the surface. Thi s combination of adsorption mechanisms controls the adsorption of fluo rine on silicon surfaces [Y. L. Li et al., Phys. Rev. Lett. 74, 2603 ( 1995); J. A. Jensen et al., Science 267, 493 (1995)]. The effects of a variety of phenomena on the adsorption kinetics are explored, includi ng surface diffusion, adlayer ordering due to adsorbate-lateral intera ctions, and the existence of weakly bound physiosorbed precursor state s. When possible, exact expressions characterizing the adsorption kine tics are derived. Otherwise, approximate expressions are derived and c ompared with Monte Carlo simulations. (C) 1997 American Institute of P hysics.