INTERACTION OF CCL4 WITH THE SURFACE OF AMORPHOUS ICE

The temperature programmed desorption of CCl4 from amorphous ice films is described. Two distinct desorption states are observed, near 130 and 145 K. In contrast to most thermal desorption systems, the lower temperature state fills exclusively at low coverages, followed by the 145 K state at higher coverages. The two states are assigned to thermal desorption of CCl4 from ice and to sublimation of the condensed CCl4 phase, respectively. Both the frequency factor and the activation energy for CCl4 desorption from ice are greater than the frequency factor and activation energy for CCl4 sublimation. This difference is attributed to hydrophobic interactions between adsorbed CCl4 and the underlying ice layer.