VUV Photon induced fluorescence study of SF5CF3

The interaction of SF5CF3 with vacuum-UV radiation has been investigated by photon induced fluorescence spectroscopy. Total fluorescence yield and dispersed fluorescence spectra of SF5CF3 were recorded in the 200-1000 nm fluorescence window. In all cases, the fluorescence spectra resemble those of CF3X (X = H, F, Cl, and Br) molecules. At photon energies below 20 eV, the emission is attributed to the excited CF3 and CF2 fragments. The threshold for the CF3 emission is 10.2 ± 0.2 eV, giving an upper limit estimate for the SF5-CF3 bond dissociation energy of 3.9 ± 0.3 eV. The excitation functions of the CF3 and CF2 emissions were measured in the photon energy range 13.6-27.0 eV. The resonant structures observed in SF5CF3 are attributed to electronic transitions from valence to Rydberg orbitals, following similar assignments in CF3X molecules. The photoabsorption spectrum of SF5CF3 shows features at the same energies, indicating a strong contribution from Rydberg excitations.