Ammonia Spectrum in the 1 cm. Wave-length Region

Abstract

IN 1933 Cleeton and Williams¹ observed a broad absorption band in ammonia at atmospheric pressure in the region of 1 cm. wave-length ; this is attributed to the 'inversion' of the pyramidal ammonia molecule which occurs when the nitrogen atom swings through the plane of the three hydrogen atoms. We have re-examined this phenomenon using a new technique, and have found that, as the pressure is reduced from 600 mm. mercury to 0.2 mm., so that the frequency of the collisions becomes small compared with the frequency of the radiation, an elaborate system of absorption lines appears.