VACUUM UV FLUORESCENCE EXCITATION SPECTROSCOPY OF CF4 AND CF3BR IN THE RANGE 45-140 NM

Fluorescence excitation spectra of CF4 and CF3Br have been measured in the range 45-95 nm and 50-140 nm respectively using synchrotron radiation. Both resonant and non-resonant peaks are observed, corresponding to neutral fragment (e.g. CF3) and parent ion (e.g. CF4+) emission. Analysis of the fluorescence has shown that bands from CF4 are due to CF3*, CF2 A B-1(1) CF4+ C 2T2. Bands from CF3Br are due to CF3*, CF2 A B-1(1) and possibly CF3Br+ E 2A1.The radiative lifetimes of all the fluorescing bands have been measured. Some of the CF3Br bands show bi-exponential behaviour. These results are interpreted by comparison with previous photoabsorption and electron energy loss spectra.