| Abstrakt: |
Trans-HONO has been photodissociated through the 220 band of the A1A‘–X 1A’ system at 355 nm. The energy disposal in the NO fragment, and vector correlations between its motions, have been characterized using polarized one-photon excited laser induced fluorescence. The rotational distribution, rotational alignment, degree of electron alignment, spin–orbit branching ratio, approximate vibrational distribution, and energy partitioning are determined. The rotational distributions in each of v(NO)=3,2 and 1 are highly inverted and approximately Gaussian in quantum number. The peak J decreases with increasing v to give a fairly narrow overall internal energy distribution. The disposal of the available energy into all NO and OH motions is 60% and 40%, respectively, and is also 40% into internal motions, mainly of NO, and 60% into translational recoil. The NO rotation shows a positive alignment. All the vector correlations are consistent with planar fragmentation dynamics, but with a finite dissociation lifetime of about 100 fs. The Λ-doublet populations of NO indicate the preference of the unpaired π electron to occupy an orbital lying perpendicular to the plane of rotation, which is opposite to that found earlier for the OH fragment. The population of the NO spin–orbit states is inverted. These results are discussed in terms of dynamical models and the features of a recently published ab initio surface for the HONO A state. [ABSTRACT FROM AUTHOR] |
