Microwave spectrum and structure of methyl phosphonic difluoride
| Autor: | David F. Plusquellic, Alan C. Samuels, Francis J. Lovas, James O. Jensen, J M. Lochner, Richard D. Suenram, M W. Ellzy |
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| Rok vydání: | 2006 |
| Předmět: |
Materials science
Spectrometer Difluoride Resolution (electron density) Analytical chemistry Atomic and Molecular Physics and Optics Isotopomers symbols.namesake Fourier transform Nuclear magnetic resonance Ab initio quantum chemistry methods symbols Molecule Physical and Theoretical Chemistry Spectroscopy Microwave |
| Zdroj: | Journal of Molecular Spectroscopy. 235:18-26 |
| ISSN: | 0022-2852 |
| DOI: | 10.1016/j.jms.2005.10.001 |
| Popis: | The rotational spectrum of methyl phosphonic difluoride has been reinvestigated using a pulsed-molecular-beam Fabry–Perot cavity microwave spectrometer. The enhanced resolution of the Fourier transform microwave (FTMW) spectrometer (compared to the original work done in a conventional Stark spectrometer) has allowed the measurement of small A – E splittings of many of the rotational transitions caused by the internal rotation of the methyl top. The barrier to internal rotation, V 3 = 676 (25) cm −1 , has been determined experimentally from the A – E splittings of the rotational transitions in the ground vibrational state. This barrier height is substantially lower than the previously determined value for the barrier, which was 1252 (14) cm −1 . High-level ab initio calculations at the MP2/aug-cc-pVTZ level predict a barrier to internal rotation of 638 cm −1 , in agreement with the experimentally determined value found here. The high sensitivity of the FTMW spectrometer has also permitted the measurement of the 13 C and 18 O isotopomers in natural abundance. The addition of these two isotopomers has allowed an improved structural determination. |
| Databáze: | OpenAIRE |
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