Knowledge Bank

Cathodochromic materials charge color when excited by an electron beam. Two modes of coloration have been observed in these materials; the optical mode is erasable by bleaching with light while the thermal mode is erasable by heating. We have obtained the infrared spectrum from 150 to 4000 $cm-1$ and the Raman spectrum of cathodochromic sodalite ($Na6Al6Si6O24\cdot 2NaBr)$ in an effort to explain the coloration modes. Spectral characteristics of colored and uncolored sodalite will be presented and interpreted. These spectra indicate a coloration model which will be compared to previously proposed $models.1,2$