LINE WIDTHS AND INTENSITIES IN RESOLVED VIBRATION-ROTATION BANDS OF $H_{3}^{*}$

Abstract

The absorption spectrum of $NH_{3}$ has been observed with high resolution in the region $2745-4720 cm^{-1}$. The conditions were varied from long paths and low pressures (1000 cm x 0.003 atm), which permits resolution and analysis of weak lines, including the K-fine-structure, to short paths (5 cm) at atmospheric pressure, under which condition the width and intensity of single isolated lines can be measured. From the high-resolution studies molecular constants have been derived for the bands listed in Table 1. Total band intensities are also given; the intensities of individual lines agree quite well in general with rigid-rotator calculations. The line widths show marked variations with J and K, paralleling those observed in the microwave region, but averaging 20% narrower. At one atmosphere pressure the lines appear quite closely of Lorentz shape out to $|\nu-\nu_{o}|=3$ $cm^{-1}$, and show no shift ($<0.03$ $cm^{-1}$) of central frequency from their low-pressure position. [FIGURE]