MULTIPHOTON IONIZATION DIAGNOSTICS FOR FLUORINATED ETHYL RADICALS: STRUCTURAL CONSIDERATIONS FOR DIFLUOROETHYL RADICALS.
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Date
1994
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Publisher
Ohio State University
Abstract
We have carried out calculational and spectroscopic investigations of several fluorinated ethyl radicals. The first electronic spectrum of the $\alpha, \alpha$-difluorethyl radical $(CF_{2}CH_{3})$ was observed between 335 nm and 475 nm by resonance enhanced multiphoton ionization (REMPI) spectroscopy. The spectrum arises form two-photon resonances with a 3p Rydberg state. A third laser photon inonized the radicals. The electronic origin is tentatively assigned at $\nu_{00}=43275 cm^{-1}$ and the vibrational progression is assigned as the $\nu_{9}{^{\prime}}(-CF_{2} wag)=530 cm^{-1}$. In support of these spectral assignments we report {ab initio} calculations at the $MP2/6-31G^{*}, G1$, and G2 theory levels which found the optimum structures, vibrational frequencies, and relative energies of $CF_{2}CH_{3}, C_{2}CH_{3}^{+}, CHF_{2}CH_{2}$, and $CHF_{2}CH_{2}{^{+}}$. These results are also discussed in the context of similar work on the analogous fluoromethyl radical $(CF_{2}H)$.
Description
Author Institution: Chemical Kinetics and Thermodynamics Division, National Institute of Standards and Technology