REFLECTANCE SPECTRA AND COLOR OF POTASSIUM AND SILVER CHROMATES IN VARIOUS MATRICES

The matrix influence on the diffuse reflectance spectra of K2CrO4 and Ag2CrO4 has been studied spectroscopically and colorimetrically. Oxide matrices (MgO, BaO, Li2CO3) were found to be inert towards the studie d compounds. In halide matrices, the symmetry decrease of the tetrahed ral CrO42- ion was observed through the appearance of the symmetry-for bidden transitions and intensity reversal. A bathochromic shift of the bands, in comparison to the results for K2CrO4, was found in the Ag2C rO4/Ag2SO4 system. It is explained under the assumption of strong cati on-anion interaction in the latter. On the basis of the color paramete rs, the halide matrices can be ordered according to their inertness to wards K2CrO4. The quantitative relationship between the matrix effect and the molecular size of the host lattice components is given for K2C rO4.