CH2
Methylene, X 3B1
Species tag 014501
Version1*
Date of EntrySep. 2005
ContributorS. Brünken
H. S. P. Müller

The dataset and the fit have been decribed in detail in
(1) S. Brünken, H. S. P. Müller, F. Lewen, and T. F. Giesen, 2005, J. Chem. Phys. 123, Art. No. 164315.
The predictions have been limited to Ka ≤ 2 because the reliability of the Ka = 3 – 2 predictions is difficult to estimate. Moreover, levels with N, Ka ≥ 2, 2 are higher than 276 cm–1 or 397 K. The partition function takes into account higher values of Ka. Transitions with Ka = 1 – 0 may be reliably predicted up to N = 8 or 9, those with Ka = 2 – 1 up to N = 6 or 7.
At lower temperatures, it may be necessary to distinguish between ortho-CH2 and para-CH2. The ortho and para levels are described by Ka + Kc = even and odd, respectively. The NKaKc = 101, J = 0 level is the lowest para state. It is 15.1270 cm–1 above ground. Nov. 2010: corrected separate para and ortho predictions are available along with separate para and ortho partition function values. NOTE: The quantum number format is different from that of the main entry; redundant quantum numbers (e.g. I) have been omitted !
The ab initio dipole moment comes from
(2) P. R. Bunker and S. R. Langhoff, 1983, J. Mol. Spectrosc. 102, 204.

Lines Listed1400
Frequency / GHz< 13069
Max. J15
log STR0-8.0
log STR1-6.3
Isotope Corr.-0.0
Egy / (cm–1)0.0
 µa / D 
 µb / D0.57
 µc / D 
 A / MHz2211494.
 B / MHz253618.1
 C / MHz215102.2
 Q(500.0)1133.5350
 Q(300.0)515.9041
 Q(225.0)332.2392
 Q(150.0)179.6201
 Q(75.00)64.1292
 Q(37.50)25.0259
 Q(18.75)13.0596
 Q(9.375)9.8503
 Q(5.000)9.0984
 Q(2.725)8.9988
detected in ISM/CSMyes


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