The microwave spectroscopy of trans-ethyl methyl ether in the ν29=1 excited torsional state

The trans-ethyl methyl ether molecule has two inequivalent methyl group internal rotors. One methyl rotor is bonded to the oxygen atom and the other to the carbon atom. The internal rotations of these methyl rotors correspond to the vibrational modes, ν29 and ν28, respectively. In this study, the microwave absorption spectrum in the ν29=1 excited torsional state was analyzed for the first time. Initial assignment has been carried out by making use of measurements at dry ice temperature. Over 1500 lines up to J=76 and K=5 were assigned. The spectrum involving internal rotation splittings was analyzed by using the tunneling matrix formulation developed by Hougen.