Millimeter wave dispersion in ethyl chloride

Dispersion of millimeter waves due to ethyl chloride in the range ν=1·34 cm^?1 to 1·44 cm^?1 is computed by means of quantum mechanical formulas. It is found that dispersion is due to (i) contribution of sixR branch rotational lines in the region considered, (ii) contribution ofR branch lines away from the region and (iii) the contribution ofQ branch lines at zero wavenumber. The maximum variation in the susceptibility is 1·9 × 10^?5 and occurs at ν=1·39 cm^?1 due to combined contribution of transitions at 1·3878 cm^?1, 1·3902 cm^?1 and 1·3927 cm^?1.