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With respect to the first entry dated Oct. 2002,
very accurate microwave data were added. These were
published by
(1) M. C. McCarthy, K. L. K. Lee, J. P. Porterfield,
P. B. Changala, and A. K. Eckhardt,
2021, Mol. Phys. 119, Art. No. e1975052.
The initial lines are from
(2) R. D. Brown, K. G. Dyall, P. D. Godfrey,
P. C. Elmes, and D. Mc Naughton,
1988, J. Am. Chem. Soc. 110, 789.
The strong hyperfine components from (1) were used
in the present fit, the weaker ones were omitted.
Hyperfine splitting is not relevant for astronomical
observations. Uncertainties of 20 kHz were now employed
for the data from (2).
Some spectroscopic parameters were estimated and
some from (1) corrected by
(3) H. S. P. Müller, 2002, unpublished.
Please note that the rotational parameter A
was erroeously floated in the initial calculation.
Its value was too large, resulting in too small
partition function values.
The calculations are accurate enough for observations
in cold sources. Ka = 0 and 1 are
probably reliable enough up to the 3 mm region.
Transitions involving higher Ka
should be viewed with increasing caution.
At low temperatures, it may be necessary to discern
between ortho-H2C3S
and para-H2C3S.
The ortho states are described by Ka odd,
the para states by Ka even.
The nuclear spin-weights are 3 and 1 for
ortho-H2C3S and
para-H2C3S, respectively.
The JKaKc =
111 level is the lowest ortho level.
It is approximately 9.6 cm–1 above ground.
The dipole moment is from (2).
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