SPECTROSCOPY AND DYNAMICS OF FAST EVOLVING STATES

This article describes several aspects of the spectroscopy and dynamics of photodissociating molecules. In particular, we report both experimental studies and theoretical models relating to the mapping of transition-state wave functions into fragment rotational distributions. A modified Franck-Condon model is described in detail for cases of modest exit-channel torques, and is applied to the dissociation of C1NO(T1), where several bending progressions are identified in the T1 dissociative state. The mapping of the wave functions in the case of large exit-channel torques are demonstrated in the dissociation of C1NO(S1) and FNO(S1). Favorable cases for mapping of parent ground- and excited-state bending wave functions into product distributions are then identified. We also describe the spectroscopic assignments of dissociative states of C1NO. Photofragment yield spectra, NO energy distributions and vector properties are used, as well as results of ab initio calculations of singlet and triplet excited states and oscillator strengths. It is concluded that definitive assignments are now possible for dissociative spectra of many small polyatomic molecules. The adiabatic evolution of NO stretch excitation into NO vibration in the dissociation of C1NO on T1 and S1 is also briefly described. The interplay between theory and experiment is emphasized throughout.