Modifications of the particle‐in‐a‐box model for the electronically excited state of solvated halide ions

Three modified particle‐in‐a‐box models for the excited state of the charge‐transfer‐to‐solvent spectra of aqueous halide ions are derived. In two of these (I and II), the halogen atom is represented as a potential well within the box, and its effect on the energy is calculated by first‐order perturbation theory. In I, the excited state is the n = 1 level of the box, and in II, the n = 2 level. In the third model (III, the halide atom is represented as a hard sphere. In this extension of the previous model, the thickness of the spherical shell between the hard sphere and the box replaces the radius of the box as the factor that determines the energy of the excited electron. This model is energetically similar to the previous one, but differs from it in that the overlap between the wavefunctions of the ground and excited states can be adjusted by varying the radius of the hard sphere.