Far infrared spectra of the tetrahydrocarbons CBr4 and CCl4

Abstract

Far infrared spectra of carbon tetrabromide in solutions of carbon tetrachloride has been measured at 20 °C in the wave number range 15–250 cm−1. The apparent dipole moments for CCl4 and CBr4 have been calculated as 0.15 and 0.31 D, respectively, on the assumption that the apparent dipole moment arises entirely from the octopole moment (Ω) of the neighboring molecules. Ω for CCl4 and CBr4 has been determined to be (13±1)×10−34 and (18±3)×10−34 esu, respectively. These values agree closely with those estimated from transition temperatures in solids composed of these molecules.