The microwave spectroscopy of trans-ethyl methyl ether in the first skeletal torsionally excited state

The microwave spectrum of the trans-ethyl methyl ether in the skeletal torsionally excited state was analyzed for the first time. The trans-ethyl methyl ether molecule has two inequivalent methyl group internal rotors but the only splitting due to the methyl group connected to the oxygen was observed. The measurement at the dry ice temperature helped the assignment of the spectrum. Over 1100 transitions up to J = 91 and K = 6 were assigned. The analysis of the spectra was carried out based on Hougen's tunneling matrix formulation.