High resolution absorption spectroscopy of NO2

The absorption cross-section of NO2 has been measured above the 3979 A predissociation limit in the region of 3920 and 3950 A and in the discretely-structured areas around 4112 and 4140 A. Spectra were taken in a dual-beam arrangement using a tunable, pulsed dye laser with 0.05-A bandwidth (FWHM). This represents an improvement of at least a factor of three over the resolution employed in previous studies. Below 3979 A, the spectra are continuous with occasional diffuse rotational lines superimposed. The spectra taken above 4100 A reveal a wealth of structural complexity. Absolute cross-sections taken at 300 K are reported. The work above 4100 A was also performed at 250 K. Only slight variations in the measured cross-sections are observed between these two temperatures. (Author)