Impurity effects on chemisorption

The influence of a substitutional impurity atom on the chemisorption properties of an adsorbate is investigated using the Green's function method. The pure solid substrate is approximated by the tight-binding scheme and the impurity is described by the Koster-Slater model. The adsorbate-impurity interaction is found to be an oscillatory function of the substrate Fermi level. Thus, depending on the kind of substrate, an impurity of a given type may strengthen or weaken the chemisorptive bond, which for molecular adsorption may lead to an increase or decrease of the rate of the subsequent dissociation process.