Knowledge Bank

The laser induced fluorescence(LIF), and laser excited, dispersed fluorescence(DF) spectra of the cyclohexoxy free radical have been observed under free-jet cooling conditions for the $B~-X~$ electronic transition. In the LIF excitation spectrum, two different types of expansions, characterized by rotational temperatures of 1 and 100 K, have demonstrated that a number of lines, termed hot bands, either nearly or entirely disappear at the lowest jet temperature. The cold spectral bands have two distinct types of structure in rotationally resolved high-resolution spectra. Correspondingly, two distinct sorts of structure are observed in the DF spectra. LIF transitions to both $a\prime$ and $a\prime \prime$ vibrational levels in the $B~$ state are observed and allowed due to a substantial pseudo-Jahn-Teller effect in the $X~$ state. We assign hot bands to transitions to the origin and excited vibrational levels of the $B~2A\prime$ state from the vibrationless level of the low-lying $A~$ electronic state. Analyses of the spectra yield vibrational frequencies for the $X~,A~$, and $B~$ states as well as the energy separations of their vibrationless levels. Although 5 conformers of cyclohexoxy are possible, it appears that all presently observed spectral bands can be accounted for by a single conformer. A more complete rotational analysis is now in progress.