VARIABLE TEMPERATURE PRESSURE BROADENING OF HNO3 IN THE MILLIMETER-WAVE SPECTRAL REGION

The O2 and N2 pressure-broadening parameters of the 18(0,18)-17(0,17), 22(7,15)-21(7,14), and 29(0,29)-28(0,28) transitions in the ground vibrational state of HNO3 have been measured in the temperature range between 100 and 380 K. Above 190 K the measurements were made in an equilibrium cell. Below 190 K, a cell with collisional cooling to circumvent the temperature limits imposed by the vapor pressure of the sample gas was used. The data were fit to the usual exponential temperature dependence with resultant n values ranging from 0.67(5) to 0.84(10) for O2 and from 0.62(3) to 0.74(9) for N2.