# RAD-3 SUBMILLIMETER-WAVE SEPECTRUM OF ACETALDEHYDE

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 Title: RAD-3 SUBMILLIMETER-WAVE SEPECTRUM OF ACETALDEHYDE Creators: Belov, Sergey P.; Tretyakov, M. Yu.; Hougen, Jon T.; Kleiner, I. Issue Date: 1992 Publisher: Ohio State University Abstract: A broad-band room-temperature submillimeter wave spectrum containing approximately 5000 lines of $CH_{3}CHO$ in the region from 165 to 417 GHz has been recorded with the RAD-3 $spectrometer^{1}$in Nizhni Novgorod (formerly Gorky). The sample pressure of approximately 0.1. Torr leads to typical linewidths of 8 MHz, which when combined with some uncertainties in the $SO_{2}$ frequencies used for calibration. Leads to measurement uncertainties of less than 1 MHz for unblended lines. We shall describe the instrument in some detail. Pure rotational transitions with J values from 10 to 20, originating in the torsional ground ($v_{t}=0$) and first excited ($v_{t}=1$) states, can be relatively easily identified using computer programs and molecular parameters determined in earlier $work^{2-4}$. Because of the broad-band spectral coverage of the RAD-3 spectrometer, these assigments can be confirmed in most cases by combination-difference loops” of 4 lines, whose frequencies sum to values less than $\sqrt{4}$ Times the 1 MHz measurement precision. The goal of the present work is not a study of $V_{t} = 0$ and 1 transition, however, but involves instead a search for lines originating in higher ($v_{t} = 2$ or 3) torsional states. We shall report on our attempts to find such lines in this RAD-3 spectrum. Description: $^{1}$ S.P. Below V.M. Demkin A.F. Krupnov and M. Yu. Tretyakov Xth International Conference on High Resolution Infrared Spectroscopy, Liblice, Czechoslvakia, 1988. $^{2}$ I. Kleiner, M. Godefroid. M. Herman and A.R. W. McKellar, J. Mol. Spectrosc. 142, 238 (1990). $^{3}$ I. Kleiner, J.T. Hougen, R.D. Suenram, F.J. Lovas and M. Godefroid, J. Mol. Spectrosc. 148, 38 (1991) $^{4}$ Kleiner, J.T. Hougen, R.D. Suenram, F.J. Lovas and M. Godefrold, J. Mol. Spectrosc. 153, 000 (1992). Author Institution: Molecular Spectroscopy laboratory, Applied Physics Institute; Molecular Physics Division, National Institute of standards and Technology; Laboratoire de Physique Mol\'{e}culaire at Applications, Universit\'{e} Pierre et Marle curie et C.N. R.S. URI: http://hdl.handle.net/1811/12834 Other Identifiers: 1992-TA-03