Temperature dependence of the optical properties of liquid benzene in the infrared between 25 and 50 °C

The vibrational properties of benzene have long been a topic of interest. A recent comparison presented in the literature of the liquid and gas intensities at 25 °C have revealed some intriguing results regarding how the interaction between the hydrogens and the neighbouring π-clouds in the liquid affect the vibrational intensities. To gain insight into the effect of temperature on the optical properties of liquid benzene and these interactions, the optical constants of liquid benzene have been determined through transmission measurements between 7400 and 800 cm−1. The spectra were measured in cells with KBr windows over a path length range of 15–1000 μm and were collected over a temperature range of 30–50 °C in 5 °C increments. Variations in the imaginary molar polarizability spectra are examined and compared to a similar study of liquid toluene completed several years ago.