VACUUM-UV FLUORESCENCE SPECTROSCOPY OF CF(3)X (X=F,H,CL,BR) IN THE RANGE 10-30 EV

The vacuum-UV and visible spectroscopy of CF(3)X (X = F,H,Cl,Br) using fluorescence excitation and dispersed emission techniques is reported . Fluorescence excitation spectra have been recorded following excitat ion using dispersed synchrotron radiation in the energy range 10-30 eV at an average resolution of approximate to 0.06 eV. By comparison wit h vacuum-UV absorption and electron energy loss spectra, assignments h ave been made for all the peaks in the Rydberg spectra of the titled m olecules that photodissociate to a fluorescing state of a fragment. Di spersed emission spectra have been recorded at the energies of all the peaks in the excitation spectra. Three distinct decay channels are ob served: (a) CF3 fluorescence for photon energies in the range 10.5 to 13.5 eV, (b) CF2 fluorescence for photon energies in the range 14.7 to 15.7 eV, (c) for photon energies in the range 20-23 eV parent ion flu orescence in the case of CF4 and CF3H, predominantly CF emission in th e case of CF3Cl and CF3Br. These assignments are confirmed by action s pectra in which the energy of the vacuum-UV radiation is tuned for det ection at a specific (dispersed) wavelength. These results confirm tho se reported in the previous paper from fluorescence coincidence experi ments that parent-ion fluorescence is the major component of the emiss ion for CF4 and CF3H excited in this latter energy range of 20-23 eV, whereas it represents only a minor component for CF3Cl and a negligibl y-small component for CF3Br.