CHF3 adsorption and decomposition on clean and oxygen covered Al(111)

The adsorption and decomposition of trifluoromethane (CHF3) on clean and oxygen dosed Al(111) were examined by means of electron energy loss spectroscopy (EELS), Auger electron spectroscopy (AES) and low energy electron diffraction (LEED). CHF3 adsorbs on the clean surface at 120 K. The coadsorption of CHF3 and chemisorbed oxygen leads to a change in the adsorption state of CHF3 indicated by the appearance of new vibrational modes in the EELS spectrum. The presence of minute amounts of oxidic oxygen that can be distinguished from the chemisorbed species has no detectable effect on the reaction behavior of CHF3. Annealing of the CHF3/oxygen adlayer to temperatures in excess of 150 K gives rise to altered EELS features that can be attributed to a decomposition of CHF3.