ORIENTATION EFFECTS IN PHYSISORBED MULTILAYERS ON CU(100)

We illustrate the use of Reflection-Absorption Infrared Spectroscopy ( RAIRS) to determine the molecular orientation of physisorbed multilaye red species. We conclude that trichloromethane orients with the C-3 ax is perpendicular to the surface and dichloromethane orients with the C -2 axis parallel to the surface. However, the orientation of physisorb ed carbon tetrachloride could not be determined from the RAIR spectra. Physisorbed diethyl ether was found to be predominantly in the form o f the trans-trans conformer with the C-2 axis tilted slightly away fro m the surface. Annealing the physisorbed films to 120 K results in cha nges in the RAIR spectrum which are attributed to ordering. No decompo sition of the molecules was observed on Cu(100).