Variable Transmission Silicate Glasses Sensitive to Sunlight

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Science  21 Sep 1962:
Vol. 137, Issue 3534, pp. 981
DOI: 10.1126/science.137.3534.981


The process of variable transmission in silicate glasses has been accomplished by optically pumping color centers by electron transfer from europium (II) or cerium (III) which absorb sunlight at higher energies than the color center. Absorbed energy quickly pumps the visible color center band to a maximum. Upon removal of activating light, the visible color spontaneously decays.