DIRECT EVIDENCE FOR BETA-HYDRIDE ELIMINATION ON SI(100)

The adsorption and decomposition of ethylbromide on Si(100)-(2X1) is i nvestigated as a way of generating surface ethyl groups. The interacti ons of ethylbromide with Si are explored by a variety of methods inclu ding ultraviolet photoelectron spectroscopy, temperature-programmed de sorption and high-resolution electron energy loss spectroscopy. Ethylb romide adsorbs molecularly on Si(100) at a surface temperature of 110 K. The C-Br bond cleaves by warming the surface to temperatures greate r than 200 K. The resulting ethyl groups decompose at surface temperat ures greater than 500 K to yield ethylene and molecular hydrogen. Deut erium labelling of the ethyl group is used to verify that the predomin ant pathway to ethylene production is through a beta-hydride eliminati on step.