EPR studies on the di-nitrogen centers with nonequivalent atoms in a reddish-brown plastically deformed diamond

Abstract

Two new di-nitrogen centers, which were labeled M2 and M3, were found together with known W7 and N4 centers in an unusual reddish-brown natural diamond. The following magnetic hyperfine interaction parameters (expressed in MHz) were determined for the two nitrogen atoms:A 1 (1) =117.95(5),A 1 (2) =A 1 (3) =84.48(5),A 2 (1) =7.1(1),A 2 (2) =A 2 (3) =6.6(1) for M2 andA 1 (1) =121.55(5),A 1 (2) =A 1 (3) =85.90(5),A 2 (1) =6.0(1),A 2 (2) =5.4(1),A 2 (3) =5.1(1) for M3. Hyperfine interaction tensors for the nitrogen atom N1 with a larger interaction have axial symmetry about the direction, but those for the other nitrogen atom, N2, appear to be small, almost isotropic. Probable models of the M2 and M3 centers are suggested and discussed.