Adsorption kinetics of chemisorption by surface abstraction and dissociative adsorption

The kinetics of diatomic molecules adsorbing onto single-crystal surfaces is considered when this process can occur by a combination of dissociative adsorption and surface abstraction. The latter process adsorbs one atom on the surface and scatters the other from the surface. This combination of adsorption mechanisms controls the adsorption of fluorine 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, including surface diffusion, adlayer ordering due to adsorbate–lateral interactions, and the existence of weakly bound physiosorbed precursor states. When possible, exact expressions characterizing the adsorption kinetics are derived. Otherwise, approximate expressions are derived and compared with Monte Carlo simulations.