Microwave Spectra, Dipole Moments, and Torsional Potential Function ofcis-Glyoxal andcis-Glyoxal-d1
✍ Scribed by H. Hübner; A. Leeser; A. Burkert; D.A. Ramsay; W. Hüttner
- Publisher
- Elsevier Science
- Year
- 1997
- Tongue
- English
- Weight
- 687 KB
- Volume
- 184
- Category
- Article
- ISSN
- 0022-2852
No coin nor oath required. For personal study only.
✦ Synopsis
Rotational transitions of cis-glyoxal, C 2 H 2 O 2 , and its monodeuterated isotopomer have been detected by microwave spectroscopy, both in their vibrational ground states and in their first and second excited torsional n 7 , as well as in their first excited n 5 bending states. Assignments have been extended to high J and K a quantum numbers which leads to higher accuracy of the spectroscopic parameters than hitherto known in the literature. Tunneling splittings of the torsionvibrational levels of 335 kHz for £ 7 Å 1 and of 42.6 MHz for £ 7 Å 2 have been observed in the glyoxal spectra. These splittings are absent in glyoxal-d 1 as is expected for symmetry reasons, while local perturbations are occasionally seen in all spectra. The electric dipole moment components have been determined for both molecules in several vibrational states where a value of m b close to 3.40 D was found in all cases. The cis-trans enthalpy difference, DH Å (18.60 { 0.57) kJ mol 01 ((1555 { 48) cm 01 ), was determined from absorption intensities of glyoxal and glyoxal-d 1 relative to those of the OCS molecule. A torsional potential function is given using DH, the cis tunneling splittings, and literature values for the frequencies of the trans and cis torsional levels as input data.