THE ADSORPTION AND THERMAL-DECOMPOSITION OF DIMETHYLZINC ON PT(111)

The adsorption and thermal decomposition of dimethylzinc (DMZ) on Pt(l ll) in the temperature range 100-400 K has been investigated by refect ion-absorption infrared spectroscopy (RAIRS). At 100 K and low exposur es, partial decomposition occurs and evidence for the CH3Zn fragment i s obtained. Further exposure results in non-dissociative adsorption of DMZ with the molecular axis oriented parallel to the surface. Adsorpt ion at 200 K initially results in complete dissociation as evinced by the detection of methyl groups bonded only to platinum. However at hig her exposures, the CH3Zn species appears to displace the surface methy l groups. Measurements indicate that CH3Zn is stable to at least 350 K . Low DMZ exposures at 400 K lead to the formation of ethylidyne which also appears to be displaced at higher exposures.