Evaluating the Solvent Stark Effect from Temperature-Dependent Solvatochromic Shifts of Anthracene.

The solvent Stark effect on the spectral shifts of anthracene is studied with temperature-dependent solvatochromic measurements. The Stark contribution Δv to the absorption shift Δv in polar solvents is measured to be Δv =(53±35) cm , in reasonable agreement with dielectric continuum theory estimate of 28 cm , whereas the major shift Δv ∼300 cm presumably originates from the solute quadrupole. We pay attention to the accurate correction of Δv for the nonpolar contribution that is crucial when the shifts are modest in magnitude.