Vacuum UV fluorescence excitation spectroscopy of CF4 and CF3Br in the range 45–140 nm

Abstract Fluorescence excitation spectra of CF 4 and CF 3 Br 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. CF 3 ) and parent ion (e.g. CF + 4 ) emission. Analysis of the fluorescence has shown that bands from CF 4 are due to CF* 3 , CF 2 A 1 B 1 and CF + 4 C 2 T 2 . Bands from CF 3 Br are due to CF* 3 , CF 2 A 1 B 1 and possibly CF 3 Br + Ẽ 2 A 1 . The radiative lifetimes of all the fluorescing bands have been measured. Some of the CF 3 Br bands show bi-exponential behaviour. These results are interpreted by comparison with previous photoabsorption and electron energy loss spectra.