Abstract

Pulsed field ionization (PFI)¹ is used to record vibrational bands from 0 to 2100 cm⁻¹ for ben-zyl^+–-h_7′, benzyl⁺–αd₂, and benzy⁺–d₇. Over 100 vibrational states are observed; assignments utilizing ab initio calculations identify 12 normal modes. Our data for benzyl⁺firmly establishes the accuracy of the calculations, which are typically 2–3% higher than experiment. Comparison of the ab initio frequencies for benzyl radical and cation show substantially greater double bond character in the exocyclic C-C bond in the cation than in that of the radical. PFI spectra recorded via each of the neutral resonances indicate the character of the vibronically mixed neutral excited states. Our data indicate that previous models of the vibronically mixed 1²A₂-2²B₂ system have included unimportant modes and have neglected important ones. We report adiabatic ionization potentials of 58464 ± 5 cm⁻¹ for benzyl⁺–h₇, 58414 ± 5 cm⁻¹ for benzyl⁺ad₂, and 58382 ± 5 cm⁻¹ for benzyl⁺–d₇.

© 1992 Optical Society of America