DENSITY EFFECTS IN THE RAMAN SPECTRUM OF AMMONIA

Abstract

The Raman spectra of ammonia as a high pressure gas, liquid, solid, and aqueous solution are compared with the spectrum of the low pressure gas. At gas pressures up to 80 atm. no appreciable hindering of rotation is present; a weak satellite of the ν1 band is an unexplained feature of the spectrum at high pressure. The spectra of the liquid, solid, and aqueous solution are interpreted without postulating dimerization; the three higher frequency maxima can be assigned to the 2ν4, ν1 and ν3 vibrations if it is assumed that hindering of rotation is almost complete. The rotational fine structure found by early workers for the aqueous solution could not be observed even at high dispersion.