The v_{10} = 1 state of propyne is the lowest excited,
doubly degenerate bending state of this molecule. It corresponds to
v_{8} = 1 of CH_{3}CN,
which has been detected in the ISM.
The rotational lines were taken from
(1) A. Bauer and J. Burie,
1969, C. R. Acad. Sci. Paris, Ser. B 268, 800;
(2) J. M. Ware and J. A. Roberts,
1984, J. Chem. Phys. 81, 1215;
(3) G. Wlodarczak, R. Bocquet, A. Bauer, and J. Demaison,
1988, J. Mol. Spectrosc. 129, 371; and
(4) H. S. P. Müller, P. Pracna, and V.M. Horneman,
2002, J. Mol. Spectrosc. 216, 397.
Transitions with the state number 1 and 2 are those with
K·l_{10} ≤ 0 and > 0, respectively.
The data have been subjected to a combined fit with the
ν_{10} band data from (4), the v = 0 data
from (4) and references therein (see also e040502.cat).
The interactions of v_{10} = 1 with
v_{9} = 1 and v_{10} = 2,
as described in (4), have been taken into account.
In particular because of these interactions,
predictions with k ≡
K·l_{10} < –11 should be viewed
with some caution. The dipole moment is assumed
to be the same as for the v = 0 state, e040502.cat.
The nuclear spinweight ratio is 2 : 1 for ACH_{3}CCH
with k + l_{10} > 0 and all other states, respectively.
The A state levels are described by k = 3n + l_{10},
those of E state by k = 3n + l_{10} ± 1.
Besides the ground vibrational state, the partition function takes
into account the states v_{10} = 1,
v_{9} = 1, and v_{10} = 2.
Their respective contributions are given in parentheses as long
as they are different from 0 within the quoted digits.
