ROTATIONAL SPECTRA OF s-trans AND s-cis GLYOXAL-d, (CHO-CDO) OBSERVED BY MICROWAVE FOURIER TRANSFORM SPECTROSCOPY

Abstract

Rotational spectra of both conformers of $glyoxal-d_{1}$ have been investigated in the 7.8 - 18 GHz region with a pulsed Fourier transform waveguide spectrometer. The asymmetric isotopic labeling induces a small permanent electric dipole moment in the s-trans conformer. Rotational constants and centrifugal distortion constants have been determined from the frequencies of 20 very weak transitions which have been assigned to s-trans $glyoxal-d_{1}$. Estimates for the deuterium quadrupole coupling constants have been obtained from the hyperfine splittings of two low J transitions. Rotational constants of the less abundant s-cis $glyoxal-d_{1}$ have been improved and all quartic centrifugal distortion constants have been determined from 16 newly assigned rotational transitions.