Photodesorption of carbonyl from Pt-3(CO)(n)(-) (n=1-6)

The photodesorption of CO from Pt-3(CO)(n)(-) (n = 1-6) has been studied in laser excitation experiments. Loss of CO is the major product channel for each species. The time-resolved profiles of photodesorption product ions ar e measured following excitation with visible laser radiation, 420-800 nm. S low fragmentation on the 10 mus-l ms time scale is observed for n = 2, 3, a nd 6. The binding energies of carbonyl in Pt-3(CO)(n)(-) (n = 2, 3, 6) are derived by fitting these time profiles using a statistical unimolecular dis sociation model. The recommended CO binding energies of Pt-3(CO)(3)(-) and Pt-2(CO)(2)(-) are 206 +/- 14 and 166 +/- 14 kJ/mol, respectively, in good agreement with previous results from threshold collision-induced dissociati on measurements. For Pt-3(CO)(2)(-) a minor second product channel Pt2CO +/ - PtCO is observed in addition to CO photodesorption. Experimental evidence suggests that there is more than one isomer for Pt-3(CO)(2)(-) species. (C ) 2001 Elsevier Science B.V.