M. Xi, B. Bent
Nov 1, 1992
Citations
1
Influential Citations
92
Citations
Quality indicators
Journal
Surface Science
Abstract
Abstract The chemistry of iodobenzene on a Cu(111) surface has been studied by Auger electron spectroscopy (AES), high resolution electron energy loss spectroscopy (HREELS), temperature-programmed reaction (TPR) spectroscopy, and work function change measurements. The results from these techniques and from H atom titration experiments show that iodobenzene dissociates at 175 K to form phenyl groups and iodine atoms and that the phenyl groups are thermally stable to above 300 K. The HREELS spectral intensities indicate that these phenyl groups bond with their π-rings approximately parallel to the surface plane. A possible reason for this unexpected adsorption geometry is the formation of phenyl anions. Biphenyl, formed by coupling of the phenyl groups, is evolved at temperatures above 300 K, while the iodine remains adsorbed on the surface until temperatures above 900 K. Comparison of the biphenyl evolution rate after iodobenzene adsorption with the rate after biphenyl adsorption indicates that phenyl coupling as opposed to biphenyl desorption is the rate-determining step in yielding biphenyl from adsorbed phenyl groups. Factors affecting the coupling rate are discussed.