Anomalous magnetic depolarization of fluorescence from the NO22B2 state

Hanle-effect studies were made of 13 identified lines belonging to the 5933-, 6117-, 6125-, and 6126-Å bands of the NO₂²B₂ state. The fluorescence was excited using a tunable cw dye laser operated single mode, using NO₂ pressures as low as 0.2 mTorr. From the variation of the fluorescence intensity with magnetic field the product gτ_C is deduced, where g and τ_C are the excited state g value and coherence lifetime, respectively. Using previously determined radiative lifetimes, g is obtained and compared to the values of g expected from Hund's case (b) coupling. The observed g values do not display the expected N′ dependence and are about an order of magnitude smaller than predicted. An alternative explanation is that the g values are behaved, but the coherence lifetime is shorter than the radiative lifetime, caused by radiationless dephasing processes which may be collisional or intrinsic.