1-Chloro-2-fluoroethane Adsorption on Cu(111):  Structure and Bonding

• Published in: The journal of physical chemistry. B 2001-11, Vol.105 (43), p.10600-10609
• Main Authors: Jones, Robert G, Chan, A. S. Y, Turton, S, Jackson, G. J, Singh, N. K, Woodruff, D. P, Cowie, B. C. C
• Format: Article
• Language: English
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/jp010016r

The adsorption of 1-chloro-2-fluoroethane on Cu(111) has been studied using low-energy electron diffraction, Auger electron spectroscopy, UV photoelectron spectroscopy, line of sight temperature-programmed desorption, and normal incidence X-ray standing wave (NIXSW) analysis. The molecule adsorbs and desorbs molecularly. The activation energy for desorption of the first layer increases linearly from 30.8 to 32.8 kJ mol-1 as the coverage increases from zero to full monolayer coverage with a preexponential of 1012 s-1. The activation energy for the multilayer is found to be 27.1 kJ mol-1 for the same preexponential value. The NIXSW structural study shows that the molecule bonds via its chlorine end, in an atop site, with a Cu···Cl distance of 3.06 ± 0.06 Å. The fluorine end, at a distance of 3.02 ± 0.1 Å from the surface copper plane, is also located approximately in an atop site. This orientates the molecule with its Cl···F axis parallel to the surface. These results are compared with similar ones for 1,2-dichloroethane and 1-bromo-2-chloroethane on Cu(111). All three molecules have similar adsorption geometries, bonding via a single halogen (the heaviest) in an atop site, while the bond strength is determined, predominantly, by this halogen.