Adsorption of Propene on Neutral Gold Clusters in the Gas Phase

The adsorption of propene on neutral gold clusters is investigated in a collision cell under a few collision conditions. The adsorption reaction is studied by pressure-dependent kinetic measurements and delayed unimolecular dissociation of the excited Au(n)propene complexes. The cluster size (n=9-25) and temperature (T=90-300K) dependence of the propene adsorption is analyzed. Strong size dependences of the absorption reaction are observed; a larger propene adsorption probability was found for gold clusters composed of an even number of atoms. Propene binding energies are estimated by comparison of the temperature-dependent unimolecular dissociation rates with rates obtained by using statistical RRKM modeling. The Au-n-propene binding energies decrease non-monotonously with cluster size and are in the range of 1.2-0.85eV for n=9-25. Finally, the bonding of C3H6 on Au-n is qualitatively described and similarities with the absorption of CO molecules on gold clusters are discussed.