Ammonia, doubly deuterated isotopic species with 15N
Species tag 020504
Date of EntrySep. 2008
ContributorH. S. P. Müller

The observed transitions were published in
(1) M. Elkeurti, L. H. Coudert, J. Orphal, G. Wlodarczak, C. E. Fellows, S. Toumi, 2008, J. Mol. Spectrosc. 251, 90
The spectroscopic parameters of NHD2 were used as starting values in the present fits. Based on the fit results it was concluded that some weak transitions from (1) may have been assigned incorrectly. The resulting parameters are consequently different from those in (1). Nevertheless, predictions for low energy transitions are beyond any doubt. Moreover, predictions with calculated uncertainties below 1 MHz should be reliable because of the extensive far-infrared data which have not been merged.
The misassignments have recently been confirmed in
(2) M. Elkeurti, L. H. Coudert, J. Orphal, G. Wlodarczak, C. E. Fellows, S. Toumi, 2010, J. Mol. Spectrosc. 260, 139
15NHD2 tunnels between two equivalent positionsas does the main species NH3. The strong c-type transitions occur between the tunneling substates whereas b-type transitions occur within the states. The antisymmetric, J = 0 state, in the catalog with the state number 1, is higher than the symmetric, J = 0 state by 0.1583 cm–1 or 4746.5 MHz. The rotational constants are average values.
In addition, one has to distinguish between ortho and para levels with a spin-statistical weight ratio of 2 : 1. In the symmetric substate, the ortho and para levels are described by Ka + Kc even and odd, respectively, while it is reversed for the antisymmetric substate. The 101 level is the lowest para and ortho level within the symmetric and antisymmetric substate, respectively. It is 9.0813 and 9.2395 cm–1 above the symmetric J = 0 level, respectively. Note, however: The ortho/para energy difference is only 0.1583 cm–1 because of the different symmetries of v = 0 and 1 ! The dipole moment was assumed to agree with that of 14NHD2; see e019501.cat.

Lines Listed2890
Frequency / GHz< 7631
Max. J21
log STR0-8.0
log STR1-6.0
Isotope Corr.-10.32
Egy / cm–10.0 / 0.1583
 µa / D 
 µb / D0.21
 µc / D1.47
 A / MHz222052.3
 B / MHz159838.8
 C / MHz112424.3
detected in ISM/CSMno

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