Collision broadening of the inversion spectrum of ammonia at centimetre wave-lengths. I. - Self-broadening at high pressure

The absorption spectrum of ammonia between 0 6 and 0.9 cm. -1 has been measured at pressures up to 60 cm Hg. From the previous analysis of the fine structure, and the measurement of the widths of the lines at a pressure of 0.5 mm. Hg, the shape of the absorption curve at high pressures has been computed assuming that the widths vary accurately as the first power of the pressure. At a pressure of 10 cm Hg, the computed and observed curves agree within the experimental error; at 60 cm. Hg, the observed attenuation at the lower frequencies is somewhat greater than that computed. Possible reasons for this phenomenon are discussed.