EPR spectra of irradiated Na₂Cr₂O₇ · 2 H₂O crystals

Abstract

The EPR spectra of X-irradiated Na,Cr,O, . 2 H,O crystals grown from the aqueous solution at room temperature are studied. Three groups of lines are detected, which marked conventionally as C,, C, and C,. Each of the C, and C, line groups is a superposition of two doublets. The lines are interpreted as due to the Cr5+ ions in the distorted (stretched) oxygenous tetrahedron. The doublet structure is due to hyperfine interaction with nuclei of 1/2 spin which are protons of water. It is shown that the C, and C, line groups are due to the centers of the same type with different orientations in the lattice. The principal gtensor values for these centres were as follows: gz = 1.916, g , = 1.978, gz = 1.986.