Electronic Absorption Spectra in Solution: with Special Reference to the Continuous Absorption of the Halogens

Abstract

The cage theory of liquids has been applied to find the form of potential function that must be added to the U(r) curves of gaseous molecules to give the U(r) curves of dissolved molecules. It is possible to explain the slight displacement of the absorption maximum in halogens dissolved in nonassociated solvents, and also the change in the symmetry of the absorption curve. The large displacement of the maximum in associated solvents is due to a slight compression of the solute molecule by the quasi‐crystalline structure of such solvents. The relaxation time of the solvent cage is such that band absorption should persist in solution when normal and excited states are of the same size; but that it should disappear when r_e′>r_e″.