The Rotation–Torsion Structure in the ν11/ν15(Gs) Methyl Rocking Fundamental Band of Dimethylacetylene

✍ Scribed by C.di Lauro; P.R. Bunker; J.W.C. Johns; A.R.W. McKellar

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 310 KB
• Volume: 184
• Category: Article
• ISSN: 0022-2852
• DOI: 10.1006/jmsp.1997.7321

✦ Synopsis

We have extended to higher frequency our earlier assignments (J. Mol. Spectrosc. 162, 142-151, 1993) of the dense rotation-torsion structure in the G s methyl rocking infrared fundamental band of dimethylacetylene (CH 3 CCCH 3 or 2butyne) centered at about 1036 cm 01 . The E 2d combination band n 4 / n 16 at 1057 cm 01 significantly perturbs this highfrequency structure, and we include its effect explicitly in the Hamiltonian matrix. We can now include considerably more of the high-frequency data in the analysis, and the new fitting leads to a determination of the ground state torsional potential parameter V 3 as 1.517 cm 01 , and a torsional barrier height (4V 3 / 4V 9 ) of 5.98 { 0.03 cm 01 . We cannot reproduce satisfactorily the structure in the immediate vicinity of the perturbation because of our lack of data for the n 4 / n 16 perturbing state.