THERMAL DISORDER IN ADSORBED CL ON SI(100)

Thermal broadening of Cl+ electron stimulated desorption ion angular d istribution (ESDIAD) patterns, related to the vibrational motion of th e adsorbate, has been investigated by subtraction of patterns measured at different temperatures. In the case of Cl on Si(100), the observed difference pattern between 130 and 305 K indicates that azimuthally i sotropic motion of Cl occurs about the most probable Si-Cl bond direct ion. Equal distributions from the in-plane and out-of-plane bending mo tions are observed, correlating with the approximately 200 cm-1 freque ncies associated with these motions.