CH3CCH, ν10
Propyne, methylacetylene, ν10 (δCCC)
Species tag 040507
Date of EntryMay 2005
ContributorH. S. P. Müller

The observed rovibrational and rotational transition frequencies have been described in
(1) H. S. P. Müller, P. Pracna, and V.-M. Horneman, 2002, J. Mol. Spectrosc. 216, 397, in
(2) P. Pracna, H. S. P. Müller, S. Klee, and V.-M. Horneman, 2004, Mol. Phys. 102, 1555, and in references therein.
The ν10 band is the lowest fundamental in propyne. Its intensity is about a factor of five weaker than that of the strongest ν9 band which is the fundamental next higher in energy. The ν10 band is a doubly degenerate vibration. State number 1 describes k values ≤ 0, while state number 2 indicates states with k > 0.
The data have been subjected to a combined fit consisting of v10 = 0, 1, 2 and v9 = 1 pure rotational data as well as ν10, ν9, and 2ν10 – ν10 rovibrational data. A stronge, isolated line has an estimated precision of 0.0002 cm–1; the accuracies are probably slightly worse because of calibration uncertainties.
The interactions of v10 = 1 with v9 = 1 and v10 = 2, as described in (1) and (2), have been taken into account.
The transition dipole moment has been estimated from the integrated band intensity measurements by
(3) S. Kondo and Y. Koga, 1978, J. Chem. Phys., 69, 4022.
Besides the ground vibrational state, the partition function takes into account the states v10 = 1, v9 = 1, and v10 = 2. Their respective contributions are given in parentheses as long as they are different from 0 within the quoted digits.

Lines Listed5634
Frequency / GHz< 11288
Max. J85
log STR0-100.0
log STR1-8.6
Isotope Corr.-0.0
Egy / (cm–1)0.0 / 330.95
 µa / D 
 µb / D0.137
 µc / D 
 A159140. / 159078.
 B8545.877 / 8596.816
 C = B
 Q(300.0)17826.0720 (4518.3010; 1040.8925, 1412.0356)
 Q(225.0)9357.5685 (1740.3447; 245.6071, 322.7121)
 Q(150.0)4209.3392 (333.2663; 17.6501; 21.7571)
 Q(75.00)1362.3596 (5.1339; 0.0144; 0.0146)
 Q(37.50)481.7197 (0.0035)
detected in ISM/CSMno

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