Adsorption of n -butane on graphene/Ru(0001) - A molecular beam scattering study

Adsorption kinetics/dynamics of n-butane on graphene, physical vapor deposited on Ru(0001) (hereafter G/Ru), and bare Ru(0001) (hereafter Ru) are discussed. The chemical activity of the supported-graphene as well as the support was probed by thermal desorption spectroscopy (adsorption kinetics). In addition and to the best of our knowledge, for the first time, molecular beam scattering data of larger molecules were collected for graphene (probing the adsorption dynamics). Furthermore, samples were inspected by x-ray photoelectron spectroscopy and Auger electron spectroscopy. At the measuring conditions used here, n-butane adsorption kinetics/dynamics are molecular and nonactivated. Binding energies of butane on Ru and G/Ru are indistinguishable within experimental uncertainty. Thus, G/Ru is "kinetically transparent." Initial adsorption probabilities, S₀, of n-butane decrease with increasing impact energy (0.76-1.72 eV) and are adsorption temperature independent for both Ru and G/Ru, again consistent with molecular adsorption. Also, S₀ of Ru and G/Ru are indistinguishable within experimental uncertainty. Thus, G/Ru is "dynamically transparent." Coverage dependent adsorption probabilities indicate precursor effects for graphene/Ru.