Table 1
Hyperfine splitting of the N = 2 ← 1, J = 3∕2 ← 1∕2 transitions.
| HFC | Frequency | AE | EL | EU | ncrit |
|---|---|---|---|---|---|
| [GHz] | [s−1] | [K] | [K] | [cm−3] | |
| F = 1−← 1+ | 2006.74892 | 0.01117 | 0.00072 | 96.31011 | |
| F = 1−← 0+ | 2006.76263 | 0.02234 | 0.00000 | 96.31005 | ~3 × 1010 |
| F = 2−← 1+ | 2006.79912 | 0.03350 | 0.00072 | 96.31252 | |
| F = 1−← 1+ | 2010.73859 | 0.01129 | 0.16071 | 96.66158 | |
| F = 1−← 0+ | 2010.81046 | 0.02257 | 0.15726 | 96.66157 | ~2 × 1010 |
| F = 2−← 1+ | 2010.81192 | 0.03386 | 0.16071 | 96.66510 | |
Notes. Data are from Pickett et al. (1998). Col. (1): hyperfine component. Col. (3): Einstein coefficient. Cols. (4) and (5): lower and upper state energy. Col. (6): critical density, AE ∕γ, for 100 K gas temperature. The collisional rate cofficients γ do not account for hyperfine splitting and are scaled by reduced mass (from He to para-H2 as collision partner, Marinakis et al. 2015).
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