Probe of the Surface of a Heterogeneous Catalyst: Double NMR of Carbon Monoxide Chemisorbed on Highly Dispersed Platinum

The detailed NMR line of exp 195 Pt atoms in the surface layer of small particles of Pt metal on which CO has been chemisorbed has been observed. The surface exp 195 Pt are resolved from the exp 195 Pt resonances of atoms deeper in the particle by spin--echo double resonance between exp 195 Pt and exp 13 C. The exp 195 Pt resonance position and exp 13 C-- exp 195 Pt indirect spin coupling are found to be very similar to those in diamagnetic Pt--carbonyl molecules. The results show that CO bonds via the carbon atom and verify that concepts deduced from studies of large single crystals are valid for the small particles. 17 ref.--AA