MICROWAVE AND SUBMILLIMETER SPECTROSCOPY OF $Ar-NH_{3}$ STATES CORRELATING WITH Ar + $NH_{3}$ ($j=1, |K|=1$)
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Date
1991
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Ohio State University
Abstract
Molecular-beam electric-resonance, electric-resonance optothermal, pulsed-nozzle Fourier-transform, and submillimeter absorption spectroscopy have been used to measure the microwave and submillimeter spectra of Ar-$NH_{3}$ for the two $\sum$ and two $\Pi$ states correlating asymptotically with $Ar +NH_{3}$ ($j=1, |k|=1$). For a number of the transitions $^{14}N$ quadrupole hyperfine structure has been resolved and relative intensity measurements have been made. The two $\sum$ states are found to lie below the two $\Pi$ states and are separated by approximately the inversion splitting of free $NH_{3}$. For the $\Pi$ states the $NH_{3}$ inversion tunneling is nearly quenched, being only weakly allowed through Coriolis interactions with the nearby $\sum$ states. The strong Coriolis interactions also give rise to a ``pure-inversion” K=0 type Q-branch with a band origin at - 22.7 GHz. All the above are interpreted using a model internal-rotation inversion Hamiltonian, leading to detailed information about the anisotropy of the intermolecular potential.
Description
Author Institution: Fysisch Laboratorium, University of Nijmegen; Molecular Physics Division, National Institute of Standards and Technology; Aerodyne Research Corporation, National Institute of Standards and Technology; Department of Chemistry, Harvard University