Absolute infrared intensity measurements on nitrogen dioxide and dinitrogen tetroxide

Abstract

The integrated intensities as a function of temperature have been measured for one NO_2 and for four N_2O_4 combination bands in the spectral region from 1 to 5µ. The temperature was varied from 50 to 100°C for the gas-phase studies and from 25 to 100°C for the liquid-phase experiments. In the spectral region from 5 to 15µ, integrated intensities at 25°C were measured for one NO_2 and for three N_2O_4 fundamental bands. Saturated vapors were used in all experiments; the optical depth was varied by using a series of spacers in a specially designed infrared absorption cell capable of handling both liquid and gas. Measured intensities for N_2O_4 combination bands in the liquid and gas phases were compared and found to differ by less than 16 per cent for three out of four combination bands studied; for the fourth band, the observed difference was about 50 per cent. Results for all of the combination bands investigated indicate that the integrated intensities vary approximately as l/T in the temperature range under consideration.