ESR SPECTRA OF Fe⁺³ IN SINGLE CRYSTALS OF ANDALUSITE

Abstract

ESR spectra of Fe +3 in andalusite have been investigated at X- and K-band frequencies at room temperature. They have been interpreted on the assumption that Fe +3 occupies the two inequivalent Al +3 sites in andalusite. The spectra show large zero-field splitting. The constants of the conventional orthorhombic spin Hamiltonian which fit the spectra are as follows: for site I: b 2 0 = 15.0 ± 0.1 kG, b 2 2 = 5.0 ± 0.1 kG, and isotropic g = 2.001 ± 0.002; for site II: b 2 0 = 20.1 ± 0.1 kG, b 2 2 = 0.075 ± 0.010 kG, and isotropic g = 2.004 ± 0.0005. A study of the intensities of ESR signals due to site I follow a pattern predicted by theory. The implications of these results are considered briefly.