INTERACTION OF CFCL3 WITH AN FE(100) SURFACE .1. ADSORPTION AND X-RAY-INDUCED EFFECTS AT 90-K

A study was made of the interaction of CFCl//3 with an Fe(100) surface over a temperature range from 90-700 K using surface sensitive techniques. A description is given of the adsorption at temperatures below 300 K. Initial adsorption on the clean Fe(100) surface at 90 K is dissociative and is followed by molecular adsorption up to approximately 6 molecular monolayers. Multilayer formation is not expected from the heat of condensation of CFCl//3. The adsorption of molecular layers therefore indicates a long-range stabilization by the substrate of the adsorbate phase. This observation is of general significance of the understanding of extrinsic precursor states in adsorption. It is observed that X-ray induced processes in the adsorbed layer which can be distinguished from thermally induced dissociation are noted.