MICROWAVE STUDIES OF COMPLEXES OF METHANOL WITH CARBON DIOXIDE AND FORMALDEHYDE
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Date
2005
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The dimeric complexes, CH$_3$OH-CO$_2$ and CH$_3$OH-H$_2$CO, were observed with pulsed-beam Fourier transform spectrometers at NIST. For the formaldehyde complex a heated reservoir nozzle was emploved and pressurized with a gas sample of 1\% methanol in either Ne or Ar carrier and the nozzle heated to about 75 $^{irc}C$. For the CO$_2$ complex, a cylinder containing 1\% methanol and 1\% CO$_2$ in Ar was used with a room temperature nozzle. Measurements were carried out from 8 GHz to 23 GHz. Both complexes exhibited internal rotation splitting due to internal rotation of the methyl group, and the formaldehyde complex showed an additional splitting on b-type transitions which is interpreted as a C$_2$ tunneling motion of the H$_2$CO monomer. Several isotopically substituted forms have also been studied for improved structure determination. The CO$_2$ complex is van der Waals bonded (C of carbon dioxide to O of the methanol), while the formaldehyde complex is hydrogen bonded (H of the hydroxyl group to O of formaldehyde). Discussion of the rotational, Stark, internal rotation, and structure analyses will be presented. These results will be compared to ab initio calculations, as well.
Description
Author Institution: Optical Technology Division, National Institute of Standards and; Technology, Gaithersburg, MD 20899-8441; Institute of Radio Astronomy of NASU, Chervonopraporna 4, 61002; Kharkov, Ukraine; Optical Technology Division, National Institute of Standards and; Technology, Gaithersburg, MD 20899-8441