Photoexcitation of 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane) to repulsive surface nσ∗(C–Br) at 234 nm: Dynamics of C–Br and C–Cl bond rupture

UV Photodissociation of Halothane in a Focused Molecular Beam: Space-Speed Slice Imaging of Competitive Bond Breaking into Spin–Orbit-Selected Chlorine and Bromine Atoms

“…Here, it is noteworthy to compare our present results with the previously reported results in ref . For both cases, the kinetic energy release distribution for Br and Br* shows a sharp peak typical of a Gaussian-like distribution.…”

“…It was found that the spin−orbit ground states of Br and Cl atoms are dominant, and this result is in good agreement with that previously reported. 30 Of crucial interest is the relative yield for the overall formation of bromine and chlorine atoms. Park et al 40 have reported the detection efficiency ratio of (2 + 1) REMPI of bromine and chlorine atoms in the photodissociation of BrCl at the present wavelength photolysis, and determined the k value to be 1.24 ± 0.30 for yields [Cl] to [Br*] in eq 5.…”

“…The shape of each kinetic energy release distribution is modeled with a frequently used functional form where f t is the energy fraction distributed into the kinetic energy channel from the available energy where E SO is the energy of the fine-structure components, the subscript i denotes each dissociation channel, and a i and b i are the adjustable parameters. For the dissociation energy of the C–Cl bond, D , 306 kJ/mol is used . The fine-structure component energy E SO of the Cl atom is taken as 0 for the ground state and 10.6 kJ/mol for the excited state, this value being the spin–orbit splitting.…”

“…By using flash photolysis of halothane at 193 nm followed by detection with VUV laser-induced fluorescence, Taketani et al 29 obtained a smaller fractional yield of the Cl atom to be 0.28 ± 0.02, suggesting an interesting variation with respect to the results of the photodissociation at a shorter wavelength. 28 Saha et al 30 have recently reported the photodissociation of halothane at 234 nm using the resonance-enhanced multiphoton ionization technique combined with time-of-flight mass spectrometry (REMPI−TOFMS), obtaining as the main channel the C−Br bond rupture accounting for ∼93%, accompanied by a significant amount of Cl scattering distribution, which was detected as bimodal. They determined the relative yield of the two spin−orbit states of halogen atoms and the branching ratio for the C−Br bond rupture against that of the C−Cl bond.…”

Electronic State Spectroscopy of Halothane As Studied by ab Initio Calculations, Vacuum Ultraviolet Synchrotron Radiation, and Electron Scattering Methods

“…Previous absolute VUV photoabsorption cross sections of halothane are available in the wavelength ranges of 250−118 nm (4.96−10.51 eV), 4 310−190 nm (4.00−6.53 eV), 3 200−310 nm (4.00−6.20 eV), 2 315−205 nm (3.94−6.05 eV), 1 and 205 nm (6.05 eV). 9 The present absolute cross sections are between 93 and 280% of the previous values. 1 −4,9 The agreement of previous cross sections measured at the ASTRID beamline with the most precise data available in the literature (see Eden et al 41 and references therein) indicate that the present halothane cross sections can be relied upon across the energy range studied (4.0−10.8 eV).…”