3-DIMENSIONAL INFINITE-ORDER SUDDEN QUANTUM-THEORY FOR INDIRECT PHOTODISSOCIATION PROCESSES - APPLICATION TO THE PHOTOFRAGMENT YIELD SPECTRUM OF NOCL IN THE REGION OF THE T-1(1(3)A'')[-S-0(1(1)A') TRANSITION -FRAGMENT ROTATIONAL DISTRIBUTIONS AND THERMAL AVERAGES

The analytical infinite order sudden (IOS) quantum theory of triatomic photodissociation, developed in paper I, is applied to study the indi rect photodissociation of NOCl through a real or virtual intermediate state. The theory uses the IOS approximation for the dynamics in the f inal dissociative channels and an Airy function approximation for the continuum functions, The transition is taken as polarized in the plane of the molecule; symmetric top wave functions are used for both the i nitial and intermediate bound states; and simple semiempirical model p otentials are employed for each state. The theory provides analytical expressions for the photofragment yield spectrum for producing particu lar final fragment re-vibrational states as a function of the photon e xcitation energy, Computations are made of the photofragment excitatio n spectrum of NOCl in the region of the T-1(1(3)A '') <-- S-0(1(1)A') transition for producing the NO fragment in the vibrational states n(N O)=0, 1, and 2. The computed spectra for the unexcited n(NO)= =0 and e xcited n(NO)=2 states are in reasonable agreement with experiment, How ever, some discrepancies are observed for the singly excited n(NO)=1 v ibrational state, indicating deficiencies in the semiempirical potenti al energy surface. Computations for two different orientations of the in-plane transition dipole moment produce very similar excitation spec tra, Calculations of fragment rotational distributions are performed f or high values of the total angular momentum J, a feature that would b e very difficult to perform with close-coupled methods, Computations a re also made of the thermally averaged rotational energy distributions to simulate the conditions in actual supersonic jet experiments. (C) 1997 American Institute of Physics.