Jet-cooled laser spectroscopy of the cyclohexoxy radical

The laser-induced fluorescence and laser-excited dispersed fluorescence spectra of the cyclohexoxy radical has been observed under two sets of free-jet-cooling conditions, characterized by rotational temperatures of approximately 1 and 100 K. Although five conformers of cyclohexoxy are possible, it appears that all presently observed spectral bands can be accounted for by a single one. All cold spectral bands are assigned to the (B) over tilde-(X) over tilde electronic transition of the cyclohexoxy radical. Transitions to both a' and a (B) over tilde state vibrational levels are observed and allowed due to a substantial pseudo-Jahn-Teller effect in the (X) over tilde state. Hot bands are also observed, which we attributed to transitions to the (B) over tilde state from the low-lying A electronic state. Analysis of the spectra yields vibrational frequencies for the (X) over tilde, (A) over tilde, and (B) over tilde states as well as the energy separations of their vibrationless levels. (C) 2004 American Institute of Physics.