The Molecular Structure of Methyl Alcohol

A qualitative discussion of the near and far infrared spectrum of methyl alcohol shows that the rotational states, including the hindered rotation, may be well represented by a model consisting of a rigid hydroxyl and a rigid methyl group. These groups may perform a mutual rotation with respect to each other about the symmetry axis of the methyl group subject to a hindering potential which is assumed to have the form $V=\frac{1}{2}H(1-cos3x)$ where $x$ is the angle of mutual rotation. A series of lines in the microwave spectrum, discovered by Hershberger and Turkevich, have recently been measured with great accuracy by Coles who also determined their Stark splitting. The positive identification of these lines leads at once to an estimate of the barrier height $H$.