The Infra-Red Absorption Spectra of Benzene and Its Halogen Derivatives

Abstract

The infra-red absorption spectra of liquid benzene and its halogen derivatives have been measured from 1.00\ensuremath{\mu} to 7.50\ensuremath{\mu}. The near infra-red bands of benzene at 2.17\ensuremath{\mu}, 2.45\ensuremath{\mu}, and 2.71\ensuremath{\mu} have been found to agree very well with the results of other observers, and several weak bands have been found which have not been previously noted. The region at 3.30\ensuremath{\mu} has been studied in detail and different maxima have been found at 3.29\ensuremath{\mu}, 3.32\ensuremath{\mu}, and 3.44\ensuremath{\mu}. The region from 5.00\ensuremath{\mu} to 7.50\ensuremath{\mu} shows five bands for benzene at 5.06\ensuremath{\mu}, 5.56\ensuremath{\mu}, 6.20\ensuremath{\mu}, 6.74\ensuremath{\mu}, and 7.16\ensuremath{\mu}. The general absorption of the halogen derivatives is very much similar to that for benzene, however, the bands differ somewhat in position of the maxima, and in the weaker bands. The more intense bands in the near infra-red have been classified as overtones or combination bands, and the agreement between calculated and observed bands is satisfactory.