# MICROWAVE SPECTRA OF THE $Ar_{3}-NH_{3}$ AND $Ne_{3}-NH_{3}$ VAN DER WAALS TETRAMERS

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 Title: MICROWAVE SPECTRA OF THE $Ar_{3}-NH_{3}$ AND $Ne_{3}-NH_{3}$ VAN DER WAALS TETRAMERS Creators: Van Wijngaarden, Jennifer; Jäger, Wolfgang Issue Date: 2001 Publisher: Ohio State University Abstract: Rotational spectra of the $Ar_{3}-NH_{3}$ and $Ne_{3}-NH_{3}$ van der Waals complexes were measured between 4 and 18 GHz using a pulsed jet Fourier transform microwave spectrometer. The isotopomers studied include those of $NH_{3}$, $^{15}NH_{3}$, $ND_{3}$, $ND_{2}H$, and $NDH_{2}$ in combination with $Ar_{3}$, $^{20}Ne_{3}$, $^{22}Ne_{3}$, $^{20}Ne_{2}^{22}Ne$, and $^{20}Ne^{22}Ne_{2}$. The isotopomers containing $Ar_{3}$, $^{20}Ne_{3}$, and $^{22}Ne_{3}$ are symmetric tops for which a-type transitions with $K=3n (n=0,1,2, \ldots)$ were observed. The other isotopomers are asymmetric tops and due to the reduced symmetry, all rotational levels are present in these complexes. For $^{20}Ne_{2}^{22}Ne$, both a- and b-type transitions were observed whereas the slightly different mass distribution in $^{20}Ne_{2}^{22}Ne$ led to the detection of a- and c- type transitions. For the deuterium containing isotopomers, each rotational transition is split by the inversion motion of ammonia within the complex. This inverison splitting is not observed in the $NH_{3}$ and $^{15}NH_{3}$ containing species for spin statistical reasons. The spectroscopic constants, including the $^{14}N$ nuclear quadrupole coupling constants, were fit for each isotopomer and used to derive structural and dynamical information for the $Ar_{3}-NH_{3}$ and $Ne_{3}-NH_{3}$ van der Waals complexes. Description: Author Institution: University of Alberta; Department of Chemistry, University of Alberta URI: http://hdl.handle.net/1811/20216 Other Identifiers: 2001-TD-02