EVIDENCE FOR AN UNUSUAL COORDINATION GEOMETRY FOR ETHYLENE ON CU(110)

Studies of ethylene adsorption on Cu(110) by temperature programmed desorption (TPD) and reflection-absorption infrared spectroscopy (RAIRS) are presented. Ethylene coordinates weakly to Cu(110) and desorbs molecularly intact below 225 K. RAIRS spectra at 100 K show two strong modes: one, the C-C stretching mode, at 1522 cm-1 and the other, the CH 2 scissors mode, at 1261 cm-1. No CH2 wagging mode is observed. These data indicate that the ethylene retains most of its pi character upon adsorption, but unlike on other transition-metal surfaces binds with its molecular plane perpendicular to the surface and its C-C bond tilted away from the surface plane.