Reactions of platinum clusters 195Ptn±, n=1-24, with N2O studied with isotopically enriched platinum

Cationic and anionic clusters 195Pt(n)(+/-) 1 less than or equal to n less than or equal to 24, were generated by laser vaporization using an isotopically enriched platinum sample. The oxidation of the clusters by nitrous oxide under binary collision conditions was investigated as a function of charge and size in a Fourier transform ion cyclotron resonance mass spectrometer. The only reaction observed is sequential addition of an oxygen atom, with the loss of molecular N-2. The reaction rates as well as the number of reaction steps exhibit a strong and irregular dependence upon the number of atoms in the cluster and its charge. These results show that isotopically enriched samples allow for the investigation of large cluster sizes together with an unambiguous assignment of reaction products and quantitative determination of rate constants.