A brief description is given of a grating spectrometer which has been used in the wavelength range 22 to 77 microns. Test measurements of the pure rotation spectrum of water vapor gave excellent agreement with other investigators. The spectrum of 1,2 dichloroethane shows bands at 409, approximately 265, and 222 cmminus;1. A band with its center a little less than 135 cmminus;1also is indicated. The value 223 cmminus;1suggested for the antisymmetric skeletal deformation frequency of thetransform of dichloroethane by Mizushima, Morino, and Simanouti is thus confirmed. Their suggestion was based on a very weak Raman band which they attributed to this infrared active frequency on the basis of a breakdown of selection rules in the liquid. Our result also confirms various statisticalhyphen;thermodynamic calculations for this substance.
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