Four Wave Mixing Spectroscopy Of The No3 B̃ 2e′ - X̃ 2a2′ Transition

The $\tilde{B}$ $^2E'$ -- $\tilde{X}$ $^2A_2'$ electronic transition of NO$_3$ generated in a supersonic free jet expansion was investigated by four wave mixing (~4WM~) spectroscopy. The degenerated 4WM and laser induced fluorescence (~LIF~) spectra around the $0_0^0$ band region were measured simultaneously. The D4WM spectrum shows broad band features for the $0_0^0$ band similar to that of the LIF spectrum. The broad $0_0^0$ band does not consist of one sub-band, but of several bands. The intensity distribution of the sub-bands of the D4WM spectrum is similar, but not identical to that of the LIF spectrum