The millimeter- and submillimeter-wave spectrum of the trans-trans conformer of diethyl ether (C2H5OC2H 5)

Abstract

Since dimethyl ether is found to have a high abundance in hot cores, it is reasonable to search among such sources for detectable abundances of the more complex analogs ethyl methyl ether (C2H5OCH3) and diethyl ether (C2H5OC2H5). Indeed, preliminary detections of both complex ethers have been reported. Definitive interstellar searches do require laboratory spectra, however, but for many years only low-frequency data have been available for both of these species. Following our recent study of the millimeter-wave and sub-millimeter-wave spectrum of ethyl methyl ether, we report here the study of the millimeter- and sub-millimeter-wave spectrum of the lowest energy conformer of diethyl ether. With four different spectrometers, over 1000 new spectral lines have been measured and analyzed at frequencies up to 350 GHz. Fitting the data to a set of spectroscopic parameters from the Watson A-reduced form of the asymmetric-top Hamiltonian has allowed us to predict the frequencies and intensities of many more transitions through 400 GHz. A more precise determination of the electric dipole moment of diethyl ether was also carried out, resulting in μ = μb = 1.0976(9)D.