Microwave Spectra of Molecules Exhibiting Internal Rotation. V. Barrier Height in Ethyl Chloride and Ethyl Bromide

The barriers to internal rotation in C2H5Cl and C2H5Br have been determined from the splittings of microwave lines in the first excited torsional state. The values obtained are V0=3560±12 cal/mole for C2H5Cl and V0=3567±30 cal/mole for C2H5Br. The influence of nuclear quadrupole hyperfine structure on the torsional splittings is discussed.