IR SPECTROSCOPY OF A PD-CARBONYL SURFACE COMPOUND

Pd is deposited onto a model alumina surface in the presence of ii CO atmosphere of 3 x 10(-6) mbar at liquid nitrogen temperatures-Accordin g to the LR spectra the palladium carbonyl compound formed contains we akly bound terminal and more strongly bound bridging CO molecules, the spectra being similar to the IR spectra of colloidal metal particles in solution and the IR spectra of CO adsorbed on small deposited Pd pa rticles. In line with thermal desorption studies of the stability of t he compound, the IR spectra reveal the transition from the compound to a situation where CO is adsorbed on larger compact metal aggregates u pon heating to room temperature. (C) 1997 Elsevier Science B.V.