Data for \(\ce{para-NH3}\) — para-Ammonia

Hyperfine Structure (2023-11-25)

For the NH₃ spectroscopy, Loreau et al. (2023) used the j_k^±F notation where ±=−ε(−1)^j is the umbrella inversion symmetry and ε is the symmetry index.

Only the hyperfine splitting due to the N nucleus is considered in these calculations. The (much smaller) hyperfine magnetic splitting due to the three protons is neglected. See Loreau et al. (2023) for more details.

Rotation-hot (2023-11-14)

For the NH₃ spectroscopy, Demes et al. (2023) used the j_k^± notation where ± =−ε(−1)^j is the umbrella inversion symmetry and ε is the symmetry index.

Because NH₃ levels (much) higher than 500 K are included in this dataset, the rate coefficients for para-H₂ have been 'thermalized', i.e. they were summed over the final states of H₂ (j₂ = 0, 2) and averaged over a thermal distribution (at the kinetic temperature) of the initial states (j₂ = 0, 2). These thermalized rate coefficients can be much larger than those for H₂ (j₂ = 0 → 0) in the case of near-resonant energy transfer between NH₃ and H₂ (see discussion in Demes et al. 2023). In contrast, the rate coefficients for ortho-H₂ are those for H₂ (j₂ = 1 → 1). These latter can also be used for higher H₂ levels, i.e. j₂ > 2.

Rotation (2021-09-18)

For the NH₃ spectroscopy, Bouhafs et al. (2017) used the j_k^ε notation where ε is the symmetry index. The umbrella inversion symmetry is equal to -ε(−1)^j.