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Details on the fit are given in
(1) A. Baudry, K. T. Wong, S. Etoka, A. M. S. Richards,
H. S. P. Müller, F. Herpin, T. Danilovich, M. Gray,
S. Wallström, D. Gobrecht, T. Khouri, L. Decin,
C. A. Gottlieb, K. M. Menten, W. Homan, T. J. Millar,
M. Montarges, B. Pimpanuwat, J. M. C. Plane, and P. Kervella,
2023, Astron. Astrophys. 674, Art. No. A125.
The parameter set and the line list are largely based on
the extensive isotopic invariant fit by
(2) B. J. Drouin,
2013, J. Phys. Chem. A 117, 10076,
which, in turn, was the basis for the entries in the JPL
catalog. The files were retrieved from the JPL catalog archive.
We thank B. J. Drouin for the availability of the files.
Two poorly determined parameters were omitted, and high-J
Λ-doubling transitions were added from astronomical
observations in (1) and in
(3) T. Khouri, L. Velilla-Prieto, E. De Beck, W. H. T. Vlemmings,
H. Olofsson, B. Lankhaar, J. H. Black, and A. Baudry,
2019, Astron. Astrophys. 623, Art. No. L1.
These data show systematic deviations with respect to the
calculation in the JPL catalog.
Please note: The quantum
numbers in the CDMS entry are Hund's case (b) quanta as always.
They are N, Λ with parity, v,
J + 0.5, and F. N + 0.5 = J
refers to Π3/2 throughout, and N –
0.5 = J to the higher lying Π1/2.
Thus, Hund's case (b) quanta are reasonable throughout.
The very extensive data set is described with references in
(2). We provide here references for the Λ-doubling
transitions and the various types of rotational and
spin-flip transitions in v = 2.
Λ-doubling transitions with microwave accuracy were
reported by
(4) W. L. Meerts, J. P. Bekooy, and A. Dymanus,
1979, Mol. Phys. 37, 425.
This publication involves measurements up to
N = 2 in Π3/2 and Π1/2.
Rotational transition frequencies with microwave accuracy were
reported by (2) and by
(5) T. D. Varberg and K. M. Evenson,
1993, J. Mol. Spectrosc. 157, 55.
Rotational data with good FIR accuracies up to N
= 10 were taken from
(6) M. A. Martin-Drumel, S. Eliet, O. Pirali, M. Guinet,
F. Hindle, G. Mouret, and A. Cuisset,
2012, Chem. Phys. Lett. 550, 8.
There are additional rovibrational lines in the data set
which include some information on the Λ-doubling at
higher rotational levels, but it is not clear if this
information is sufficient. Therefore, Λ-doubling
transitions above 70 GHz should be viewed with some
caution, above 100 GHz with considerable caution.
Some caution is also advised for rotational transitions
and transitions involving spin-flip if the calculated
uncertainties exceed 1 MHz.
The partition function was evaluated by summing over
all states up to F = 50 and v = 9. While the
partition function is essentially converged at 3000 K,
model deficiencies may make it advisable to view values
at 2000 K and higher with some caution.
The v = 1 dipole moment was determined in
(7) K. I. Peterson, G. T. Fraser, and W. Klemperer,
1984, Can. J. Phys. 62, 1502.
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