A study of 13C hyperfine structure in the EPR of nickel-nitrogen-containing centres in diamond and correlation with their optical properties
A study of 13C hyperfine structure in the EPR of nickel-nitrogen-containing centres in diamond and correlation with their optical properties
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DOI：
10.1088/0953-8984/11/38/314
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发表时间：
1999-09
期刊：
影响因子：
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通讯作者：
V. Nadolinny;A. Yelisseyev;J. Baker;M. Newton;D. Twitchen;S. Lawson;O. Yuryeva;B. Feigelson
中科院分区：
文献类型：
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作者：
V. Nadolinny;A. Yelisseyev;J. Baker;M. Newton;D. Twitchen;S. Lawson;O. Yuryeva;B. Feigelson
电子顺磁共振（EPR）和光学光谱已被用来确定天然金刚石和合成金刚石中富含13 C的镍-氮中心的结构和电子状态。后者生长在Fe-Ni-C溶剂/催化剂系统在1750 K，在稳定的压力下，通过温度梯度法，然后在高温和高压下处理。NE 1中心的13 C超精细结构（HFS）张量的参数和方向被发现证实了先前提出的模型，这种缺陷，与镍离子在中心的双半空位作为基本结构单元。在这个单元中，镍原子在其配位壳层中有六个原子。NE 1中心具有C2 h对称性，配位壳层中的两个等效氮原子位于对称平面内。NE 5中心的14 N和13 C的HFS的新数据，也具有C2 h对称性，表明相同的结构单元，但两个等效的氮原子（和两个等价的碳原子）位于对称平面之外，并通过在其中的反射而彼此相关。发现了一个新的顺磁中心，标记为NE 8，也具有C2 h对称性，配位壳层中的四个等效氮原子都位于对称平面之外。该中心负责吸收和发光光谱中的793.6 nm振动系统。新的数据允许重新解释NE 2中心的HFS张量，它具有C1对称性，这表明它具有与NE 1相同的结构，但在配位壳层中有一个额外的氮原子。这些含镍中心的电子状态进行了讨论，使用的方法Ludwig和伍德伯里过渡金属离子在共价晶体。
Electron paramagnetic resonance (EPR) and optical spectroscopy have been used to determine the structure and electronic state of nickel-nitrogen centres in natural diamonds and in synthetic diamonds enriched in 13C. The latter were grown in an Fe-Ni-C solvent/catalyst system at 1750 K, under stabilizing pressure, by the temperature gradient method and afterwards treated at high temperature and pressure. The parameters and directions of the 13C hyperfine structure (HFS) tensors for the NE1 centre were found to confirm the previously proposed model for this defect, with a nickel ion at the centre of a double semivacancy as the basic structural unit. In this unit the nickel atom has six atoms in its coordination shell. The NE1 centre has C2h symmetry, and the two equivalent nitrogen atoms in the coordination shell lie in the symmetry plane. New data on the HFS of 14N and 13C for the NE5 centre, also with C2h symmetry, indicated the same structural unit, but the two equivalent nitrogen atoms (and two equivalent carbon atoms) lie out of the symmetry plane and are related to one another by reflection in it. A new paramagnetic centre was found, labelled NE8, also with C2h symmetry, with four equivalent nitrogen atoms in the coordination shell all lying out of the symmetry plane. This centre is responsible for the 793.6 nm vibronic system in absorption and luminescence spectra. The new data have allowed a reinterpretation of the HFS tensors for the NE2 centre, which has C1 symmetry, suggesting that it has the same structure as NE1 but with one additional nitrogen atom in the coordination shell. The electronic states of these nickel-containing centres are discussed using the approach of Ludwig and Woodbury to transition metal ions in covalent crystals.