Methane; monodeuterated isotopolog
Species tag 017503
Date of EntryJune 2009
ContributorsH. S. P. Müller
B. J. Drouin

This entry is a combined CDMS and JPL entry.
The J" = 0, 1 transition frequencies were taken from
(1) M. Womack, A. J. Apponi, L. M. Ziurys, 1996, Astrophys. J. 461, 897.
The J" = 2 and 3 transition frequencies were reported by
(2) V. Lattanzi, A. Walters, J. C. Pearson, and B. J. Drouin, 2008, J. Quant. Spectrosc. Radiat. Transfer 109, 897.
In addition, infrared ground state combination differences were used in the fit. These were published in
(3) C. Chackerian, Jr., and G. Guelachvili, 1980, J. Mol. Spectrosc., 84, 447;
(4) C. Chackerian, Jr., E. S. Bus, W. B. Olson, and G. Guelachvili, 1986, J. Mol. Spectrosc., 117, 255;
(5) O. N. Ulenikov, G. A. Onopenko, N. E. Tyabaeva, J. Schroderus, and S. Alanko, 1999, J. Mol. Spectrosc. 193, 249
With respect to the Mar. 2008 entry, the J" = 4 transitions from (2) have been remeasured, and the J" = 6 transitions have been measured with high accuracy for the first time. The data have been published in
(6) B. J. Drouin, S. Yu, J. C. Pearson, and H. S. P. Müller 2009, J. Quant. Spectrosc. Radiat. Transfer 110, 2077.
Descrepancies of the data from (3) with those in (5) and (6) were traced to a calibration error in (3); details are described in (6).
The predictions are thought to be fairly reliable throughout.
At low temperatures, it may be necessary to discern between A-CH3D and E-CH3D. The A state levels are described by K = 3n, those of E state by K = 3n ± 1. The nuclear spin-weight ratio is 2 : 1 for A-CH3D with K > 0 and all other states, respectively. The JK = 11 level is the lowest E state level. It is 9.1306 cm–1 above ground.
The dipole moment and distortion corrections were taken from
(7) J. K. G. Watson, M. Takami, and T. Oka, 1979, J. Chem. Phys. 70, 5376.
As the distortion effects are rather large the intensities should be viewed with increasing caution beyond J of about 8.

Lines Listed143
Frequency / GHz< 4829
Max. J21
log STR0-8.0
log STR1-9.0
Isotope Corr.-3.944
Egy / (cm–1)0.0
 µa / D0.0057
 µb / D 
 µc / D 
detected in ISM/CSMno

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