AB INITIO ROTATION-VIBRATION SPECTRA OF $\tilde{X} ^{2}\Sigma^{+} MgNC$
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Date
2001
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
In 1986 Gu\'elin $et al.^{b}$ found, in radio astronomical observations, six transitions originating in the circumstellar envelope of the late-type carbon star $IRC+10216$. No assignment of these lines could be given at the time, but they were later $identified^{c,d}$ as belonging to the rotational spectrum of the MgNC radical. Thus, MgNC became the first Mg-containing molecule to be identified in interstellar space. The only rotationally resolved, spectroscopic data presently available for $\tilde{X} ^{2}\Sigma^{+}$ MgNC comprise the rotational $spectrum^{c,e}$ together with a few vibronic bands, all originating in the vibronic ground state and belonging to the $\tilde{A} ^{2}\Pi\leftarrow\tilde{X} ^{2}\Sigma^{+}$ electronic $transition.^{f}$ In the hope of stimulating further characterization of $\tilde{X} ^{2}\Sigma^{+}$ MgNC by high resolution spectroscopy, we report here ab initio simulations of its lowest $\tilde{X}$-state rotation-vibration bands. The calculations are carried out with the MORBID program $system,^{g}$ and they are based on a previously calculated potential energy function using ACPF $method,^{h}$ supplemented with dipole moment surfaces computed with $CASSCF/[TZ3P+f(Mg)$, aug-cc-pVQZ(N andC)].
Description
$^{a}$Special Visiting Professor of the Japanese Ministry of Education, Science and Culture, October-December 2000. Permanent address: FB 9 - Theoretische Chemie, Bergische Universit\""at - Gesamthochschule Wuppertal, D-42097 Wuppertal, Germany. $^{b}$M. Gu\'elin, J. Cernicharo, C. Kahane, and J. Gomez-Gonzales, Astronomy \& Astrophysics 157, L19 (1986) $^{c}$K. Kawaguchi, E. Kagi, T. Hirano, S. Takano, and S. Saito, Astrophys. J. 406, L39 (1993) $^{d}$K. Ishii, T. Hirano, U. Nagashima, B. Weis and K Yamashita, Astrophys. J. 410, L43 (1993) $^{e}$M. A. Anderson and L. M. Ziurys, Chem. Phys. Lett. 231, 164 (1994); E. Kagi, K. Kawaguchi, S. Takano, and T. Hirano, J. Chem. Phys. 104, 1263 (1996) $^{f}$R. R. Wright and T. A. Miller, J. Mol. Spectrosc. 194, 219 (1999) $^{g}$See, for example, Section 15.4.7 of P. R. Bunker and P. Jensen, Molecular Symmetry and Spectroscopy, NRC Research Press, Ottawa, 1998, and references therein. $^{h}$T. Kinoshita and T. Hirano, 17th Austin Symposium on Molecular Structure, Abstracts, 48 (1998).
Author Institution: Faculty of Science, Ochanomizu University; Department of Chemistry, Faculty of Science, Ochanomizu University; Department of Chemistry, Ibaraki University
Author Institution: Faculty of Science, Ochanomizu University; Department of Chemistry, Faculty of Science, Ochanomizu University; Department of Chemistry, Ibaraki University