The observed rovibrational and rotational transition
frequencies have been described in
(1) H. S. P. Müller, P. Pracna, and V.M. Horneman,
2002, J. Mol. Spectrosc. 216, 397, in
(2) P. Pracna, H. S. P. Müller, S. Klee, and V.M. Horneman,
2004, Mol. Phys. 102, 1555,
and in references therein.
The ν_{10} band is the lowest fundamental
in propyne. Its intensity is about a factor of five weaker
than that of the strongest ν_{9} band
which is the fundamental next higher in energy.
The ν_{10} band is a doubly degenerate vibration.
State number 1 describes k values ≤ 0,
while state number 2 indicates states with k > 0.
The data have been subjected to a combined fit consisting of
v_{10} = 0, 1, 2 and v_{9} = 1
pure rotational data as well as ν_{10}, ν_{9},
and 2ν_{10} – ν_{10}
rovibrational data.
A stronge, isolated line has an estimated precision of
0.0002 cm^{–1}; the accuracies are probably
slightly worse because of calibration uncertainties.
The interactions of v_{10} = 1 with
v_{9} = 1 and v_{10} = 2,
as described in (1) and (2), have been taken into account.
The transition dipole moment has been estimated from
the integrated band intensity measurements by
(3) S. Kondo and Y. Koga,
1978, J. Chem. Phys., 69, 4022.
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.
