Analysis of an Electron Spin Resonance Spectrum in Natural Diamonds

Abstract

An anisotropic electron spin resonance spectrum was observed in three natural Type Ib diamonds. The diamonds which exhibit the spectrum also show the spectrum from substitutional nitrogen donors previously observed by others. The spectrum consists of three anisotropic groups of lines. The spectrum is interpreted in terms of a model in which each defect center is characterized by a spin Hamiltonian of the form $\mathcal{H}\mathrm{=\beta }\mathbf{S·g·H}\mathrm{+}\mathbf{A·I·S}$ , where S = ½ and I = 1, and in which the tensors g and A each have one component g₁ and A₁ oriented in a 〈110〉 direction. The spin‐one nucleus is believed to be nitrogen. The principal components of g and A have the values g₁ = 2.0031±0.0003, g₂ = 2.0019±0.0003, g₃ = 2.0025±0.0003, A₁ = 5.303±0.005×10⁻⁴ cm⁻¹, A₂ = 7.164±0.005×10⁻⁴ cm⁻¹, and A₃ = 5.293±0.005×10⁻⁴ cm⁻¹. The components g₂ and A₂ make angles Ψ = 45.2°±0.3° and α = 22.4°±0.1°, respectively, with 〈110〉 directions. The theoretical angular dependencies of the spectra when the magnetic field H is rotated in {100}, {110}, and {111} crystalline planes were calculated on the basis of the above model and are in excellent agreement with the experimentally observed angular behaviors.