Microwave Spectrum of Ethyl Iodide, II.

The potential barrier which hinders the internal rotation in ethyl iodide molecule was studied. If the potential energy is assumed to be of the sinusoidal form \(H/2(1-cos\ 3x)\), the barrier height is determined as H =3.22±0.5 kcal/mole from the Q b -type transition in the first excited torsional state. The torsional frequency is about 230 cm -1 . The effect of internal rotation on the quadrupole hyperfine structure of K =1 levels was analyzed.