Observation of Isolated Carbon Atoms and the Study of Their Mobility on Pt Clusters by NMR

Abstract
The authors have used NMR to determine the structure of surface species after the C-C bond scission of adsorbed acetylene and ethylene on Pt clusters produced by heating the samples to 690 K. They have found the species to be predominantly isolated carbon atoms adsorbed on Pt surfaces. They have studied the mobility of adsorbed carbon atoms from motional narrowing of the C13 line shapes and motion-induced shortening of the spin-lattice relaxation times. They have found that the carbon atoms on Pt clusters are very mobile, their activation energy of 7 ± 1 kcal/mole for translational motion being less than half of CO on Pt clusters.