Vacuum UV photoabsorption spectroscopic and photoionization mass spectrometric study of geminal dibromoethylene (1,1-Br2C2H2) in the 5–15eV range. Experiment and theory

The vacuum UV photoabsorption spectrum of 1,1-dibromo-2,2-difluoroethylene (1,1-Br2C2F2) in the 5-15 eV photon energy range. Combining experimental and theoretical investigations

“…This sequence logically follows the trend of the ionization energy IE vert of the respective ˜ X 2 B 1 ground state, i.e. 10.688 eV [17] , 9.677 eV [4] and 9.40 eV calculated in the present work.…”

“…5 , the E exc vert ( π v * ) for the valence transition is considerably shifted to lower energy 1,1-H 2 C 2 F 2 > 1,1-Br 2 C 2 F 2 > 1,1-Br 2 C 2 H 2 at 7.482 eV [16] , 6.920 eV and 6.231 eV [4] respectively. With respect to 1,1-Br 2 C 2 H 2 [4] the π * state is strongly stabilized, i.e. + 0.689 eV, by the 2,2-substitution of H 2 by F 2 .…”

“…+ 0.689 eV, by the 2,2-substitution of H 2 by F 2 . Contrarily, the lowest Rs Rydberg state is continuously destabilized on substitution 1,1-H 2 C 2 F 2 > 1,1-Br 2 C 2 H 2 > 1,1-Br 2 C 2 F 2 at 6.957 eV [16] , 6.583 eV [4] and 6.18 eV respectively. This sequence logically follows the trend of the ionization energy IE vert of the respective ˜ X 2 B 1 ground state, i.e.…”

“…At the present state of our investigation of the halogenated derivatives of ethylene a comparison could be made with the low-energy side of the vacuum UV PAS of 1,1-C 2 H 2 F 2 [15] and 1,1-C 2 H 2 Br 2 [4] . In the range of 5.0 eV to 8.0 eV the most important features are the π (nb 1 ) → π * valence-and the lowest Rydberg π (nb 1 ) → Rs Rydberg transitions.…”