| The spectroscopy and photodissociation dynamics of nitric oxide dimer, (NO)2 and chloromethyl radical, CH2Cl, are studied using the velocity map ion imaging (VMI) and resonance enhanced multiphoton ionization (REMPI) techniques. Vector and scalar properties of the photodissociation dynamics are elucidated through examination of the product state, angular and translational energy distributions. Observed quantities are compared with statistical and dynamical models.; (NO)2 photolysis is investigated in the 222--213 nm UV region with VMI and the 2.5-1.4 mum IR region with REMPI yielding NO(A2 Sigma+) + NO(X2pi) and NO(X 2pi) + NO(X2pi), dissociation products, respectively. In the UV, the correlated product state distributions near dissociation threshold agree with the predictions of phase space theory while those at higher excess energies display deviations, especially for high NO(X2pi) rotational levels. The angular distributions indicate that [NO(A2Sigma +), NO(X2pi)] product pairs with high NO(X) rotational levels are produced preferentially via planar dissociation, in contrast to the statistical expectation of the v · J correlation, which reveals no preference for planar dissociation. A dissociation mechanism involving vibrational predissociation with restricted intramolecular vibrational energy redistribution is invoked.; In the IR, photofragment yield spectra and NO(X2pi 1/2, 3,2; v = 1, 2, 3) product vibrational, rotational, and spin-orbit distributions were measured. New bands that include the symmetric nu 1 and asymmetric nu5 NO stretch modes were observed. Dissociation occurs primarily via Deltav=-1 processes with vibrational energy confined preferentially to one of the two NO fragments. The vibrationally excited fragments are produced with less rotational energy than predicted statistically and the NO spin-orbit distribution reveals a slight preference for the ground spin-orbit state. It is suggested that the long range potential in the N-N coordinate is the locus of nonadiabatic transitions to electronic states correlating with excited product spin-orbit states.; The photodissociation of CH2Cl is studied by the ion imaging technique. Cl photofragments are produced via simultaneous excitation of perpendicular and parallel electronic transitions. The relative populations and translational energy distributions of Cl fragments generated via each transition are extracted. H-atom products, which are detected in a one-color experiment at 243.1 nm, exhibit an angular distribution characteristic of perpendicular transitions only. |
