FEATURE STATE ASSIGNMENT AND HIERARCHICAL AND STATISTICAL-ANALYSES OFVIBRONIC AND ROVIBRONIC LEVEL STRUCTURE OF NO2 IN THE 16300-25130-CM(-1) REGION

The laser induced fluorescence (LIF) spectrum of jet-cooled NO2 in the energy range from 16 300 cm(-1) up to the dissociation limit at 25 13 0.6 cm(-1) was measured with an energy resolution of 0.4 cm(-1), and v ibronic interaction was discussed through a feature state assignment a nd a hierarchical analysis. By convoluting the spectrum, the feature s tates representing bending excited levels in the B-2(2) state were ide ntified. The hierarchical level structure just below the dissociation limit was interpreted in terms of a stepwise intramolecular vibronic e nergy redistribution (IVR) caused by the anharmonic couplings within t he B-2(2) state followed by the vibronic and rovibronic couplings betw een the B-2(2) and (2)A(1) states. In a higher resolution (similar to 0.04 cm(-1)) measurement the transitions to the rovibronic eigenstates just (0-55 cm(-1)) below the dissociation limit were resolved. The ob served vibronic level density having b(2) symmetry, rho(vib)(b(2))=1.6 /cm(-1), in this energy region is derived from the observed peak densi ty, rho(peak)=9.6/cm(-1), by assuming a strong K mixing. The observed large peak density was ascribed to the large anharmonisity of the grou nd state potential energy surface near the dissociation limit. The sta tistical analyses applied to this eigenstate spectrum Showed an extrem ely strong correlation among these eigenstates, indicating the complet e IVR. The present results of the statistical analyses near the dissoc iation limit support the statistical behavior in the dissociation dyna mics just above the dissociation limit investigated in our previous pa per [J: Chem. Phys. 99, 254 (1993)].