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 ν₁₀ band is the lowest fundamental in propyne. Its intensity is about a factor of five weaker than that of the strongest ν₉ band which is the fundamental next higher in energy. The ν₁₀ 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 v₁₀ = 0, 1, 2 and v₉ = 1 pure rotational data as well as ν₁₀, ν₉, and 2ν₁₀ – ν₁₀ 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 v₁₀ = 1 with v₉ = 1 and v₁₀ = 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 v₁₀ = 1, v₉ = 1, and v₁₀ = 2. Their respective contributions are given in parentheses as long as they are different from 0 within the quoted digits.