# ROTATIONAL SPECTROSCOPY AND STRUCTURE OF SEVERAL $NH_{3}$ COMPLEXES

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 Title: ROTATIONAL SPECTROSCOPY AND STRUCTURE OF SEVERAL $NH_{3}$ COMPLEXES Creators: Fraser, G. T.; Nelson, D. D.; Leopold, K. R.; Klemperer, William Issue Date: 1984 Publisher: Ohio State University Abstract: The radiofrequency and microwave spectrum of $NH_{3}-CO_{2}$ has been measured using the molecular beam electric resonance technique. The spectrum is characteristic of an asymmetric top in which the $NH_{3}$ subunit exhibits effectively free internal rotation. The spectroscopic constants obtained for the ground internal rotor state are presented below. [FIGURE] The $N-CO_{2}$ framework of the complex has $C_{2v}$ symmetry with an N-C weak bond length of $2.9875(4) {\AA}$. The average bending angle of the $NH_{3}$ subunit is $22.71(5)^{\circ}$ with a difference in amplitude of $1.0(4)^{\circ}$ between the in plane and out of plane excursions. (B+C)/2 for the first excited state ($|m|=1$) is 3753.008(2) MHz and the quadrupole coupling constant $eQq_{aa}(|m|=1) -3.176(9) MHz$ is identical with that measured for the ground internal rotor state. The rotational spectrum of the similar complex $NH_{3}-N_{2}O$ has also been obtained. The spectrum is complicated by the quadrupolar hyperfine and internal rotation and we are attempting to obtain the structure and three-fold barrier height for this system. While studying various $NH_{3}$ complexes an intense and complicated spectrum was observed for $ArNH_{3}$. The spectral complexity and observed frequencies demonstrate that this complex is not a symmetrical top. Description: Author Institution: Department of Chemistry, Harvard University URI: http://hdl.handle.net/1811/16597 Other Identifiers: 1984-FC-3