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 studied compounds. In halide matrices, the symmetry decrease of the tetrahedral CrO42- ion was observed through the appearance of the symmetry-forbidden transitions and intensity reversal. A bathochromic shift of the bands, in comparison to the results for K2CrO4, was found in the Ag2CrO4/Ag2SO4 system. It is explained under the assumption of strong cationanion interaction in the latter. On the basis of the color parameters, the halide matrices can be ordered according to their inertness towards K2CrO4. The quantitative relationship between the matrix effect and the molecular size of the host lattice components is given for K2CrO4.
T. Tłaczała, M. Cieślak-Golonka, A. Bartecki, and M. Raczko, "Reflectance Spectra and Color of Potassium and Silver Chromates in Various Matrices," Appl. Spectrosc. 47, 1704-1711 (1993)