MILLIMETER WAVE SPECTRUM OF THE $NH_{3} - N_{2}$ COMPLEX

$^{a}$Present address: Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada $^{b}$G.T. Fraser, D.D. Nelson, Jr., K.I. Peterson, and W. Klemperer, J. Chem. Phys. 84, 2472 (1986) $^{c}$K.A. Walker and A.R.W. McKellar, J. Mol. Spectrosc. 205, 331 (2001).Author Institution: Department of Chemistry, National Research Council of Canada; Steacie Institute for Molecular Sciences, National Research Council of CanadaThe only previous spectroscopic study of the ammonia - nitrogen van der Waals complex was made by $Fraser et al.^{b}$ in 1986. They observed one main $K = 0$ series of rotational transitions, $R(0)$ to $R(3)$, in the 6 to 27 GHz region using the MBER technique. Another pair of lines near 13.5 GHz (reported in a footnote) was evidently the first member, $R(1)$, of a series with $K = 1$. We have studied the $NH_{3} - N_{2}$ spectrum in the 76 to 106 GHz region using a newly-developed pulsed jet millimeter wave $spectrometer.^{c}$ Thirty-five lines were observed and assigned as $R(11)$ to $R(15)$ pure rotational transitions, belonging to six series which involve all combinations of the parent molecule nuclear spin species, ortho/para ammonia and ortho/para nitrogen. Two of these series are continuations to higher J-values of the transitions observed in the microwave $region,^{b}$ and the remaining four series are new. We are thus able to predict a number of new microwave transitions for $NH_{3} - N_{2}$ whose observation will help to confirm the present assignments of K-values and spin species