Study of alkyl chain propagation by electron beam dissociation of methyl groups on Cu(1 1 0)

Abstract Electron irradiation on adsorbed methyl groups on Cu(1 1 0) at 90 K to produce coadsorbed methylene groups is observed by HREELS. The cross-sections for CH 2 (ads) production and CH 3 (ads) desorption are determined at 15 eV e-beam energy. In TPD measurements, CH 2 (ads) groups mainly react with CH 3 (ads) to generate gaseous ethylene, propylene, and butene with desorption peaks centered all at 310 K independent of the CH 2 (ads) surface concentration. The product ratio of C 3 H 6 /C 2 H 4 is linearly proportional to the ratio of CH 2 (ads)/CH 3 (ads). The results suggest that aggregation of the adsorbates and close proximity of the reactants are critical for the chain propagation reaction.