Hyperfine structure of EPR spectra of Cr5+ ions in irradiated sodium dichromate crystals

Abstract

AbstractEPR spectra are studied of X‐irradiated sodium dichromate crystals grown from an aqueous solution by evaporation at 31°C. Doublet lines of EPR‐absorption are attributed to the Cr5+ ions in the CrO43− and CrO3− radicals resulting from radiation decomposition of Cr2O72− and being in the lattice in two unequivalent positions. Hyperfine structure caused by interaction of an unpaired electron with Cr53 nucleus were observed both at liquid nitrogen and room temperatures. For the line, caused by CrO43− radical, gy and Ay directions coincide and angles both between Ax, gx and Az, gz make up ∼ 25°. The spectrum is described by usual spin Hamiltonian for S = 1/2 with following parameters (T = 77 K): for CrO: gz = 1.984, gy = 1.970, gx = 1.961, |Az| = 8.2 · 10−4 cm−1, |Ay| = 13.7 × 10−4 cm−1, |Ax| = 36.1 · 10−4 cm−1; for CrO3−: gz = 1.915, gy = 1.975, gx = 1.985, |Az| = 32.2 · 10−4 cm−1.