Solvent effects on electronic spectral oscillator strengths

The effect of long‐range dispersion forces on the conversion from the total integrated absorption of an allowed solute transition in solution to the corresponding unperturbed oscillator strength in the isolated solute is investigated. As an illustration of this effect, calculations are performed on the $1s → 2p$ transition of an H solute in a variety of inert and other gases. The commonly used Lorentz field correction factor $(n02+2)2/9n0$ is shown to be of minor importance compared to an additional ``IMF'' factor arising from the intermolecular forces between the solute and the solvent molecules and the translational fluctuations between the induced moments. While the former factor is always greater than one, the latter can be greater than as well as less than unity. Implications regarding more complex solutes are considered.