Optical Constants and Dipole Moment Derivatives of Bromobenzene between 3200 and 400 cm −1 at 25 °C

Abstract

The optical constants (real and imaginary refractive indices) of bromobenzene were determined at 25 °C via transmission measurements. Experimental absorbance spectra measured on a Nicolet Impact 410 FT-IR were converted to imaginary refractive indices by using methods described in the literature. The real refractive indices were obtained by Kramers-Kronig transformation of the imaginary refractive indices. The complex refractive indices were used to calculate the molar absorption coefficient (E_m) and complex molar polarizability (_m) spectra. The integrated intensities and dipole moment derivatives with respect to normal coordinates for the fundamentals were obtained from the areas under the bands in the α“_m spectrum. These dipole moment derivatives were compared to those obtained from the spectra of chlorobenzene in the literature. It was found that, in general, the dipole moment derivatives displayed very little dependence on the substituent, even for some of the vibrations for which the wavenumber is substituent sensitive.