VIBRATIONAL COUPLING BETWEEN ETHYLIDYNE SPECIES ON PLATINUM PARTICLES

Vibrational coupling between neighboring ethylidyne species adsorbed on a Pt/Al2O3 catalyst has been detected using an equimolar mixture of (CH3C(a))-CK-13 and (CH3C(a))-CK-12. The coupling is detected by means of the development of increased intensity sharing in the symmetric CK-H deformation mode for the chemisorbed ethylidyne species as the ethylidyne coverage increases. The results indicate that ethylidyne is produced from ethylene on (111) facets of small Pt particles, rather than on random trimer Pt sites which might also exist on the catalyst. Experiments on highly dispersed Pt catalyst surfaces have failed to detect ethylidyne production.