PTMS on iron and aluminium oxide surfaces: a study of damped adsorption kinetics

The kinetic processes taking place during the adsorption of propyltrimethoxysilane (PTMS) onto polycrystalline iron and aluminium oxide surfaces have been investigated using X-ray photoelectron spectroscopy. Although the adsorption of PTMS on iron reaches equilibrium within a few seconds, the adsorption of PTMS on aluminium exhibits a dramatic time dependence. The presence of a single oscillation in the adsorbate coverage as a function of time indicates the existence of two distinct surface species, each of whose coverage varies dynamically, confirming the predictions of an earlier model.