The Millimeter- and Submillimeter-Wave Spectrum and the Dipole Moment of Ethylenimine

✍ Scribed by S. Thorwirth; H.S.P. Müller; G. Winnewisser

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 209 KB
• Volume: 199
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1999.7992

✦ Synopsis

The rotational spectrum of ethylenimine (aziridine, c-C 2 H 4 NH) has been investigated in selected regions from 118 to 950 GHz using the Cologne terahertz spectrometer. About 320 lines have been measured spanning the quantum numbers 2 Յ J Յ 59 and 0 Յ K c Յ 50. All lines have been fit together with previously published data to yield refined ground state constants such as A ϭ 22 736.19294(31) MHz, B ϭ 21 192.46114(31) MHz, and C ϭ 13 383.16401(30) MHz and centrifugal distortion constants that permit accurate frequency predictions. FTMW measurements were performed at the ETH Zu ¨rich to redetermine the dipole moment, to improve 14 N-quadrupole-coupling constants, as well as to determine 14 N-spin-rotation coupling constants. The most reliable values for the components of the dipole moment are b ϭ 0.97(12) D and c ϭ 1.357(25) D determined by the Stark-and additional intensity measurements of appropriate b-and c-type transitions. Moreover, we performed quantum chemical calculations of the dipole moment of ethylenimine that confirm these experimental results. This three-membered ring molecule is of potential astrophysical interest.