Infrared intensities of liquids XXII: Optical and dielectric constants, molar polarizabilities, and integrated intensities of liquid benzene-d(6) at 25 degrees C between 5000 and 450 cm(-1)

Abstract

This paper presents accurate infrared absorption intensities of liquid benzene-d(6) at 25 degrees C, between 5000 and 450 cm(-1). The results are presented as graphs and tables of the real, n, and imaginary, Ic, refractive index spectra, which are also called the optical constant spectra. The real refractive index is shown between 8000 and 450 cm(-1). The absolute errors in the k values are estimated to be similar to 3% below, and up to 60%, above 4700 cm(-1), with those in the n values similar to 0.25% throughout. The Beer-Lambert molar absorption coefficient spectra, E-m((v) over tilde), and the complex dielectric constant spectra, epsilon'((v) over tilde) and epsilon "((v) over tilde), were calculated from the optical constant spectra. To correct for macroscopic dielectric effects, the complex molar polarizability spectra, alpha(m)' and alpha(m)"((v) over tilde), were calculated from the dielectric constant spectra under the Lorentz local field. The properties of bands in these different spectra are compared. The imaginary molar polarizability spectra were fitted convincingly to 208 Classical Damped Harmonic Oscillator bands, and the areas under the corresponding (v) over tilde alpha(m)" bands gave the integrated intensities C-j. These were assigned as far as possible and are tabulated. The transition dipole moments of well assigned transitions, and for the infrared-active fundamentals, under the double harmonic approximation, the dipole moment derivatives with respect to the normal coordinates, were calculated from the values of C-j, and are presented. This appears to be the first extensive measurement of the infrared absorption intensities of liquid benzene-d(6). The results are compared with Literature data for liquid and gaseous benzene-d(6).