Adsorption and desorption kinetics of oxygen on the Pd(110) surface

The adsorption and desorption of oxygen on a Pd(110) surface have been investigated by temperature-programmed desorption (TPD). A number of TPD spectra for associative desorption of O 2 from O/Pd(110) were taken at constant heating rate with different initial coverages and at constant initial coverage with different heating rates. The TPD curves were analyzed by the desorption rate isotherm and desorption rate isostere methods. The variations in apparent Arrhenius parameters with coverage were obtained by fitting to the Polanyi–Wigner equation. First-order associative desorption kinetics was found, suggesting the effect of lateral interaction and oxygen-induced added-row reconstruction. Two different processes for associative desorption of oxygen from the O/Pd(110) surface were found. The sticking probability for dissociative adsorption of O 2 on the Pd(110) surface has been measured as a function of surface coverage and surface temperature by using two mass spectrometers. The sticking probability profile suggested a precursor trapping–dissociation mechanism. The initial sticking probability was independent of surface temperature.