Reactions of size-selected platinum cluster ions, Pt n + (n ) 1-5), with small hydrocarbon molecules (CH 4 , C 2 H 6 , C 2 H 4 , and C 2 H 2 ) were studied in a beam-gas cell geometry at collision energies less than 1 eV employing a tandem mass spectrometer. It was found that dehydrogenation of the hydrocarbon molecules proceeds exclusively on Pt n + and the absolute cross sections of the reactions depend critically on the cluster size, n, and the collision energy. The size-and the collision energy-dependent cross sections are successfully explained in an RRK framework.

Absolute cross sections for the reaction of a benzene molecule with a nickel cluster cation with the sizes of 3−11 were measured in a beam-gas cell geometry at collision energies less than 1 eV in a tandem mass spectrometer. Three different reaction processes were found to proceed:  benzene chemisorption with and without Ni release and dissociative chemisorption with C2H2 release. The size-dependent reaction cross sections were explained in terms of a statistical model.