Influence of saturation with hydrogen on the structure and spectroscopic properties of optical centers in Co- and Cu-containing silica gel-glasses

In Co- and Cu-containing silica gel-glasses vitrified in air, the activators existed as oxide complexes of Co(II), Co(III), Cu(I) and Cu(II). Annealing of these glasses in hydrogen at temperature ≤800°C leads to reduction of cobalt to the doubly charged state and reduction of copper to the metallic state. An increase in the annealing temperature by 100–300°C results in a deterioration of the optical quality of the glass because of light scattering.