Table 1
Properties of the NH2D and NH3 transitions.
| Molecule | Quantum numbers | Frequency | Upper energy level | Statistical weight | Aij | Critical density | Reference |
|---|---|---|---|---|---|---|---|
| (GHz) | (K) | of upper/lower level | (s−1) | (cm−3) | |||
| NH2D ortho | 111–101 | 85.926 | 20.7 | 27 | 7.82 × 10−6 | 6.52 × 104 (a) | CDMS (c) |
| NH2D para | 111–101 | 110.154 | 21.3 | 9 | 1.65 × 10−5 | 1.38 × 105 (a) | CDMS |
| NH2D para | 212–202 | 74.156 | 50.7 | 15 | 5.92 × 10−6 | 6.18 × 104 (a) | CDMS |
| NH3 para | 1,1 a–1,1 s | 23.694 | 23.3 | 6 | 1.68 × 10−7 | 1.95 × 103 (b) | JPL (c) |
| NH3 para | 2,2 a–2,2 s | 23.722 | 64.4 | 10 | 2.24 × 10−7 | 2.03 × 103 (b) | JPL |
Notes. (a) The de-excitation rate coefficients are taken at 10 K from Daniel et al. (2014). (b) The de-excitation rate coefficients at 15 K from Danby et al. (1988) are used. (c) The statistical weight given by CDMS includes a factor three for the rotation quantum number, a factor three for the spin of the two H atoms, and the N nuclear spin multiplicity of three. On the contrary, JPL does not include the nuclear spin of N.
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