Laser-induced fluorescence spectroscopic study of the Ã2A1X̃ 2E transition of trifluoromethoxy radical

Revealing Long-Range Substituent Effects in the Laser-Induced Fluorescence and Dispersed Fluorescence Spectra of Jet-Cooled CHxF3-xCH2O (x = 1, 2, 3) Radicals

The B̃-X̃ laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of the atmospherically important β-monofluoro ethoxy (MFEO), β,β-difluoro ethoxy (DFEO), and β,β,β-trifluoro ethoxy (TFEO) radicals were recorded with vibronic resolution under jet-cooled conditions. To simulate the spectra, Franck-Condon factors were obtained from quantum chemical computations carried out at the CAM-B3LYP/6-311++G(d,p) level of theory. The simulations reproduce well both the LIF and DF spectra. Both conformers (G and T) of MFEO and one (G) of the two conformers of DFEO contribute to the LIF spectrum. A comparison between the experimental and calculated spectra confirms the expected long-range field effects of the CH_xF_3-x group on electronic transition energies and bond strengths, especially in the excited electronic (B̃) state. Although TFEO has only one conformer, its LIF spectrum is highly congested, which is attributed to the interaction between CO stretch and the -CF₃ internal rotation.

Rotational Analyses of the Laser Induced Fluorescence Excitation Spectra of Jet-Cooled CF3O and CF3S

The high resolution, rotationally resolved laser induced fluorescence spectra for the A2A1 left and right arrow X2E transitions of CF3O and CF3S were recorded. In addition to the origins, the symmetric vibrational band 301 and the nontotally symmetric bands 501 and 601 were analyzed for CF3O, while for CF3S the symmetric bands 101, 201, and 301, as well as the nontotally symmetric bands 601, 301501, and 301601, were analyzed. Copyright 1997 Academic Press. Copyright 1997Academic Press

Do Hydrofluorocarbons Destroy Stratospheric Ozone?

Hydrofluorocarbons, many of which contain a CF(3) group, are one of the major substitutes for the chlorofluorocarbons and halons that are being phased out because they contribute to stratospheric ozone depletion. It is critical to ensure that CF(3) groups do not cause significant ozone depletion. The rate coefficients for the key reactions that determine the efficiency of the CF(3) radical as a catalyst for ozone loss in the stratosphere have been measured and used in a model to calculate the possible depletion of ozone. From these results, it is concluded that the ozone depletion potentials related to the presence of the CF(3) group in hydrofluorocarbons are negligibly small.