PHOTODISSOCIATION OF JET-COOLED NO2 AT 355 NM - STRONG ALIGNMENT AND OSCILLATIONS IN THE ROTATIONAL STATE DISTRIBUTIONS OF THE NO(V''=1) FRAGMENT

State-to-state photodissociation of NO2 at 355 nm has been investigate d by means of jet-cooling and one-photon laser-induced fluorescence pr obing techniques. The rotational distribution of nascent NO(v''=1) fro m the fast predissociation of efficiently cooled NO2 shows pronounced oscillations of each spin-orbit and LAMBDA-doublet component and bimod al distributions with preferred population at low and high J. Strong d eviations from the statistical distributions of phase space theory are found. Alignment measurements for NO(v''=1,J>5.5) from the dissociati on of slowly rotating parent molecules are reported for the first time . The well-preserved rotational alignment with a fairly constant value of A0(2) = -(0.35 +/- 0.05) confirms that photodissociation at this w avelength is initiated by a 2A1/B-2(2) <-- 2A1 parallel electronic tra nsition with less than 5% contribution from another possible perpendic ular transition B-2(1) <-- 2A1. The characteristic rotational distribu tions observed thus arise from this 2A1/B-2(2) <-- 2A1 transition. Our results clearly show that the energy flow among product rotational de grees of freedom is far from complete and that dynamical effects have to be considered important in the predissociation of NO2 via the groun d-state surface.