Fluorescence lifetime studies of NO2. II. Dependence of the perturbed 2B2 state lifetimes on excitation energy

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Abstract
Radiative lifetimes and quenching rates of the perturbed 2B2 state were measured, using pulsed Nd–YAG laser excitation between 473 and 659 nm. The decay of broad band (3000 to 9000 cm−1) fluorescence is nearly exponential at low pressures (P?0.1 mtorr) for excitation wavelengths less than 562 nm. Lifetimes increase smoothly from 88 μsec at λE=473 nm to 120 μsec at 562 nm. Low pressure decays at 659 nm are nonexponential with at least two components of 124 and 200 μsec. The excitation energy dependence of the radiative lifetime and the change from exponential decays at higher energies to nonexponential decays at lower energies is explained by assuming that the 2B2 state couples strongly to high vibrational levels of the ground state.