Pressure Broadening of the Rotational Line of Oxygen at 425 GHz

The pressure broadening of the ¹⁶O¹⁶O rotational line (N, J)=(3, 2)-(1, 2) at 425 GHz by oxygen and nitrogen perturbers at room temperatures have been reported. A spectrometer with BWO and acoustic detector was employed with a double magnetically shielded cell. The signal-to-noise ratio on the line was about 200-250 for self-broadening and about 100 for broadening by N₂ measurements. The pressure-broadening parameters of the line at room temperature (23±0.5°C) were measured as 2.19±0.01 MHz/Torr for self-broadening and 2.215±0.02 MHz/Torr for broadening by nitrogen. Values of these parameters significantly (by about 25%) differ from ones previously measured by H. M. Pickett, E. A. Cohen, and D. E. Brinza, (Astrophys. J.248, L49-L51 (1981)). The results of the present work show the necessity for correction of broadening parameters of this line for the purpose of Earth atmosphere remote sensing. The central frequency of the transition (N, J)=(3, 2)-(1, 2) was measured as 424 763.023±0.020 MHz.