Xi. Zhou et al., SYNTHESES AND REACTIONS OF VINYL AND PHENYL FRAGMENTS ON AG(111), Journal of the American Chemical Society, 115(10), 1993, pp. 4309-4317
Low-energy electron activation of monolayer ethylene and benzene, adso
rbed on Ag(111) at 100 K, leads selectively to vinyl and phenyl fragme
nts. An electron impact ionization model, followed by rapid reneutrali
zation and C-H bond cleavage, is proposed. Upon heating, neither fragm
ent undergoes further C-H or C-C bond cleavage; rather, both undergo c
arbon-carbon coupling to form 1,3-butadiene and biphenyl. When coadsor
bed with methyl or ethyl fragments, temperature-programmed desorption
yields propene or 1-butene for vinyl, whereas it yields toluene or eth
ylbenzene for phenyl. Kinetic parameters describing the electron-stimu
lated fragment synthesis and the subsequent thermal reactions were det
ermined in the presence and absence of atomic iodine.