Microwave optical double resonance of NO2 with a tunable cw dye laser: Spin-rotation and hyperfine interactions in the 2B2 excited electronic state

Various spin and hyperfine components of the 6₁₆ → 7₀₇ microwave transition in the ²B₂ electronic excited state were observed by microwave optical double-resonance spectroscopy using a tunable cw dye laser near 593 nm. Spin splittings and the hyperfine structure of two levels were precisely determined. Spin-rotation and hyperfine interactions in the ²B₂ state are discussed using these and the previously reported results on the 8₁₈ → 9₀₉ transition. From the hyperfine splittings of the K_a = 0, N = 7 and 9 levels, a value for the Fermi contact interaction constant, (0)_I, of ～50 MHz was determined.