Photophysics of CF3NO

We use laser spectroscopic methods to measure fluorescence lifetimes of CF3NO. These lifetimes correspond to radiationless decay from specific torsional and other vibrational levels of the S1 state of CF3NO. The lifetime data and collisional quenching studies are used to support a model of S1 internal conversion to S0, followed by dissociation to CF3+NO. Relative changes in radiationless rates as a function of optical excitation are successfully calculated by a radiationless rate theory. The torsional mode is proved to be a promoting mode for the radiationless transition, which is the first example of this concept. The predicted vibrational and torsional populations in S0 are used to make specific predictions of trends in the rotational and vibrational energy content of the NO photofragment.