Magnetic circular dichroism of the 1.404-eV interstitial nickel absorption transition in high-pressure synthetic diamond

Abstract

A high-resolution magnetic circular dichroism ͑MCDA͒ study of the sharp 1.404-eV zero-phonon absorption line associated with interstitial nickel in high-pressure synthetic diamond is reported. A model is presented attributing the absorption to internal transitions within the 3d 9 configuration of Ni i ϩ , as perturbed by the cubic field at the diamond interstitial site, plus a smaller trigonal crystal field. The model provides a consistent explanation of the signs of the circular absorption coefficients of all the observed transitions plus the unusual features of the g values observed for the ground (g Ќ ϳ0) and excited (g ʈ ϳ0) states. A search for an optically detected magnetic resonance in the MCDA was unsuccessful, consistent with the forbidden magnetic resonance transition for an Sϭ1/2, g Ќ ϭ0 ground state. ͓S0163-1829͑99͒13231-4͔PRB 60 5423 MAGNETIC CIRCULAR DICHROISM OF THE 1.404-eV . . .

Investigation of nickel lattice sites in diamond: Density functional theory and x-ray absorption near-edge structure experiments

“…From an experimental point of view, the various lines detected by electronic paramagnetic resonance (EPR) [31][32][33][34][35][36] or by magneto-optical (including magnetic circular dichroism) or piezo-optical spectroscopy 21,[37][38][39] have been attributed to specific incorporation sites of Ni in diamond. This has been a challenge since the early days when it was recognized that an isolated Ni atom was incorporated in a site of trigonal symmetry at low temperatures (below 25 K) changing over to a tetrahedral symmetry at higher temperatures.…”

CASSCF calculations for photoinduced processes in large molecules: Choosing when to use the RASSCF, ONIOM and MMVB approximations

“…Nickel has been shown to form point defects in natural and synthetic diamonds [125][126][127][128][129][130] . Mason et al 131 have characterized an interstitial Ni defect in diamond, with transitions between ground and excited levels measured at ~1.4eV. Here we investigate computationally the geometries and energetics of the ground and excited states of an interstitial nickel defect in diamond.…”

Estrutura eletrônica e campo hiperfino de impurezas complexas de cobalto e de níquel em diamante

“…O centro NIRIM-2 foi identificado com spin S = 1/2 e apresentando uma forte distorção trigonal [11,58,59]. A estrutura microscópica para este centro está, ainda, sujeita a controvérsias.…”

“…O centro estudado apresentava simetria axial, valores de g e muito maiores que o do elétron livre, e um espectro hiperfino compatível com um spin nuclear I = 7/2, característico do núcleo de 59 Co. Uma análise detalhada destes resultados, juntamente com a aplicação do modelo de LW, levouà conclusão de que este centro deveria ser descrito por uma impureza de cobalto, com configuração eletrônica 3d 7 , em um sítio intersticial tetraédrico distorcido (C 3v ou D 2d ), em estado de carga duas vezes positivo, (Co i ) 2+ . No entanto, estes resultados nunca foram reproduzidos.…”

“…Assim, 59) onde n ′ jé o número de todas as outras espécies e mantido fixo. Quando utilizamos processos em que se mantém a pressão e a temperatura constantes, aúltima relação, equação (3.59),é a mais conveniente.…”