SiC2, v3 = 4
Silacyclopropynylidene, v3 = 4 (Extrapolation)
Species tag 052538
Version1*
Date of EntryOct. 2015
ContributorH. S. P. Müller

SiC2 is a cyclic molecule with a fairly low barrier to linearity which is probably responsible for the large centrifugal distortion effects, especially in excited vibrational states involving excitation of v3. The v3 mode can be considered as asymmetric SiCC bending motion or as the C2 internal rotation motion. Ka odd are permitted only in contrast to Ka even for the ground vibrational state. This is because of the different vibrational symmetry.
The v3 = 3 transition frequencies have been estimated from lower v data. The combined fit is described in
(1) R. C. Fortenberry, T. J. Lee, and H. S. P. Müller, 2015, Mol. Astrophys., 1, 13.
The recently extended set of ground state transition frequencies was summarized in
(2) H. S. P. Müller, J. Cernicharo, M. Agúndez, L. Decin, P. Encrenaz, J. C. Pearson, D. Teyssier, and L. B. F. M. Waters, 2012, J. Mol. Spectrosc., 271 50;
further details can be found there or in the ground state documentation e052527.cat. Transitions for v3 = 1 and 2 come mainly from
(3) M. Izuha, S. Yamamoto, and S. Saito, 1994, Spectrochim. Acta A, 50, 1371.
Additional v3 = 1 data were taken from
(4) M. Bogey, C. Demuynck, J. L. Destombes, and A. D. Walters, 1991, Astron. Astrophys., 247, L13.
The predictions have been truncated at 400 GHz and at Ka = 8. All predictions should be viewed with great caution. It is conceivable that predictions involving low values of J or Ka are quite reasonable.
The dipole moment was assumed to agree with that in the ground vibrational state, see e052527.cat; it is possible that this assumption is not as good as usually !
NOTE: The partition function takes into account the ground vibrational state only. However, contributions of excited vibrational states to the partitionfunction are available. For corrections much higher than 200 K, a list of vibrational energies is also available.

Lines Listed122
Frequency / GHz< 400
Max. J19
log STR0-8.0
log STR1-4.5
Isotope Corr.-0.0445
Egy / (cm–1)605.33
 µa / D2.393
 µb / D 
 µc / D 
 A59860.
 B12588.0
 C9475.0
 Q(300.0)5208.0814
 Q(225.0)3375.3615
 Q(150.0)1833.7985
 Q(75.00)647.6255
 Q(37.50)229.2305
 Q(18.75)81.3646
 Q(9.375)29.0251
 Q(5.000)11.6560
 Q(2.725)5.4248
detected in ISM/CSMno


Database maintained by Holger S. P. Müller and Sven Thorwirth, programming by D. Roth and F. Schlöder