THE INVERSION SPECTRUM OF $NH_{3}$ IN THE ${000}^{0}1^{1}$ STATE
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Date
1972
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Ohio State University
Abstract
The inversion spectrum of $NH_{3}$ in the ${000}^{0}1^{1}$ state (degenerate bending mode) was observed at $300^{\circ} K$ using a Hewlett-Packard 8400 Microwave Spectrometer with a three foot cell. Nineteen transitions have been assigned in the frequency range 26.3 - 40.6 GHz. These are the K = J, ${\ell} = -1$ sequence from J = 1 to 12, the K = J-1, ${\ell} = -1$ sequence from J = 2 to 7 and the J, K, ${\ell} = 2, 2, + 1$ transition. The first sequence was extrapolated to give an inversion frequency of $1.0976 {\pm} 0.0001 cm^{-1}$ to which the IR values of $1.01 cm^{-1a}$ and $1.047 cm^{-1b}$ are compared. Changes with inversion state of the constants B, C, $C\zeta, \eta_{J}, \eta_{K}$ are determined to within changes in higher order constants. Differences from the IR values are largely a reflection of the differences in precision of the methods. The 2, 2, -1 and 3, 2, -1 levels are perturbed by matrix elements of the form $< J, K, \ell H J, K \pm 4, \ell=2 >$ which displace the lines by + 47 MHz and - 235 MHz respectively.
Description
This research was supported under NASA Contract No. NAS 7-100. The authors also wish to thank the Pomona Operation, Electrodynamics Division, General Dynamics Corporation for use of its spectrometer. $^{a}$ J.S. Garing, H.H. Nielsen and K.N. Rao, J. Mol. Spectrosc. 3, 496 (1959). $^{b}$ R.E. Walker and B.F. Hochheimer, J. Mol. Spectros. 34, 500 (1970).""
Author Institution: Space Sciences Division, Jet Propulsion Laboratory, California Institute of Technology
Author Institution: Space Sciences Division, Jet Propulsion Laboratory, California Institute of Technology