Abstract
The infra-red absorption spectra of liquid benzene and its halogen derivatives have been measured from 1.00μ to 7.50μ. The near infra-red bands of benzene at 2.17μ, 2.45μ, and 2.71μ 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 3.30μ has been studied in detail and different maxima have been found at 3.29μ, 3.32μ, and 3.44μ. The region from 5.00μ to 7.50μ shows five bands for benzene at 5.06μ, 5.56μ, 6.20μ, 6.74μ, and 7.16μ. 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.