Absorption Spectra of Excess Electrons in Alkali‐Halide Salt Melts

Abstract

AbstractAbsorption spectra of excess electrons in pure and mixed alkali halide melts, periodically injected by ac‐electrolysis, were investigated by a modulation technique. The wide spectra without structure resemble those of solvated electrons in polar solvents: they have their maxima in the red to the near infrared, they are shifted to longer wave length with increasing temperature, their maximum extinction coefficient is larger than 104 M−1 cm−1. Similar to the excess electrons in solid salts (F‐centres) ‐ however with a larger proportional factor ‐ the wave length of maximum absorption increases with the square of the mean ion distance which is calculated from the density of the melts. ‐ The data can be interpreted by the theory of an electron in a box which had been applied to the F‐centres before. The larger half width of the spectra and the larger proportional factor of the quadratic relationship in the melts in comparison to those in the solids are due to the fluid state with the highly mobile ions.