Studies of lifetimes of rotationally cooled NO2 using time-resolved fluorescence excitation spectra

A taunble, pulsed dye laser with output in the region of 5750 to 6000 Å was used to excite rotationally cooled NO₂ which was produced by expansion in conjunction with argon carrier gas through a supersonic nozzle. The resulting time-resolved fluorescence excitation spectra were used the lifetimes of various vibronic bands of NO₂ (²B₂). The lifetimes measured were in the region of 15 to 40 μs which were shorter than those obtained from cell experiments. For each individual excitation wavelength, only a single exponential decay was observed from very early times through 250 μs.