Infrared intensities of liquids XXV: Dielectric constants, molar polarizabilities and integrated intensities of liquid toluene at 25 °C between 4800 and 400 cm−1

The main purpose of this paper is to present accurate infrared integrated intensities of liquid toluene, C6H5CH3, at 25 °C. Also presented are the decadic molar absorption coefficients, Em, the real and imaginary dielectric constants, ε′ and ε″, and the real and imaginary molar polarizabilities, α′m and α″m. Integrated intensities were determined as Cj, the area under bands in the ν˜α″m spectrum, for all bands between 4800 and 440 cm−1. The contributions from the different bands were separated by fitting the spectrum with classical damped harmonic oscillator bands. The uncertainties in the integrated intensities of most bands are estimated to be 5-10%, with the uncertainties in very weak bands and in shoulders possibly up to 100%. The intensity that should be assigned to the fundamentals is more difficult to estimate due to Fermi resonance with overtone and combination bands, and a best estimate is given. The integrated intensities of the fundamental vibrations and the corresponding transition dipole moments are summarized and are compared with literature values for the gas.