Electronic spectral intensities in binary solvent mixtures

Abstract

A systematic study on the intensities of n-π^∗ band of benzophenone in various binary solvent mixtures has been carried out with a view to investigate the behaviour of electronic band intensities in different environments. Possibilities of relating band intensities to equilibrium constants of dipole-dipole and other complexes, solvent compositions and dielectric constants of binary solvent mixtures have been examined. It is found that in all the cases plots of C_p/∈ vs. C_p and (D-D₀)/ vs. (D-D₀)-where ∈ is the extinction coefficient of n-π^∗ transition of benzophenone in a solvent mixture containing C_p moles of perturbing solvent, D is the dielectric constant of the solvent mixture and D₀ the dielectric constant of the assumed nonperturbing solvent-were very good straight lines. Similar behaviour was also shown by the infrared band intensity data given in the literature.