Submillimeter spectrum of NH3−H2O dimer in its equilibrium gas phase

The first observation of the microwave spectrum of the NH₃–H₂O molecular complex in its equilibrium gas phase is reported. Earlier, the spectrum of NH₃–H₂O was observed only in nonequilibrium cold supersonic molecular beams. As in the previous paper [1] dealing with the observation of the equilibrium spectrum of HF-HF dimer, we use a submillimeter spectrometer with a BWT and acoustic detector and a cooled absoprtion cell. The submillimeter line frequencies continuing the series known from the beam investigations have been measured. New series, which obviously correspond to the higher states of the dimer, have been detected. The primary results of the analysis of the dimer spectrum together with the earlier data are presented.Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia; Molecular Physics Department, National Institute for Standards and Technologies, USA. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 7, pp. 738–742, July, 1995.