Knowledge Bank

The infrared spectrum of trifluormethane adsorbed onto alkali halide films was observed. The C-H stretch $(\nu 1)$ is shifted $42cm-1$ to the blue of the gas phase value, while the C-F stretch $(\nu 2)$ is only slightly shifted to the red. There are also noticeable splittings in the degenerate modes $(\nu 4,\nu 5)$ that disappear in multilayer coverage. The effects of substrate and temperature on the observed spectrum will be discussed. The observed vibrational shifts and desorption kinetics will be compared with those derived form the calculated potential of adsorption.