Effect of Pressure on Absorption Spectra of Lycopene in n-Hexane and CS₂ Solvents

The absorption spectra of lycopene in n-hexane and CS₂ are measured under high pressure and the results are compared with β-carotene. In the lower pressure range, the deviation from the linear dependence on the Bayliss parameter (BP) for β-carotene is more visible than that for lycopene. With the further increase of the solvent BP, the 0-0 bands of lycopene and β-carotene red shift at almost the same rate in n-hexane; however, the 0-0 band of lycopene red shifts slower than that of β-carotene in CS₂. The origins of these diversities are discussed taking into account the dispersion interactions and structures of solute and solvent molecules.