Anharmonicity effects in impurity-vacancy centers in diamond revealed by isotopic shifts and optical measurements
Anharmonicity effects in impurity-vacancy centers in diamond revealed by isotopic shifts and optical measurements
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同位素位移和光学测量揭示了金刚石中杂质空位中心的非调和效应
DOI：
10.1103/physrevb.95.094113
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发表时间：
2017
影响因子：
3.7
通讯作者：
M. Kondrin
中科院分区：
文献类型：
--
作者：
E. Ekimov;V. Krivobok;S. Lyapin;P. Sherin;V. Gavva;M. Kondrin
我们研究了同位素富集的纳米和微米金刚石与光学活性中心合成在高压和高温下的非金属生长系统。同位素组成对光学性质的影响已经通过光致发光激发（PLE）和光致发光（PL）光谱进行了深入研究，以深入了解该色心的性质和电子结构。我们已经证明，大的频率缺陷（在基态和激发电子态的振荡频率之间的差异）确实带来了PLE和PL谱之间的较大差异和相对较高的零声子线的同位素位移。这两种效应对于分裂空位中心（例如，频率缺陷达到创纪录的高值）似乎相当普遍。碳原子在金刚石晶格中的同位素取代导致甚至更大的位移，这仅部分地由金刚石晶格的体积变化引起的电子密度的重新分布来解释。结果表明，在这种情况下的振动频率不依赖于碳原子的质量。这种同位素位移的最大部分是由于非谐效应，这构成了在这个中心观察到的电子振动频率的重要组成部分。然而，导致取代的非谐性显著增强的确切物理机制尚待阐明。
We studied isotopically enriched nano- and microdiamonds with optically activecenters synthesized at high pressures and high temperatures in nonmetallic growth systems. The influence of isotopic composition on optical properties has been thoroughly investigated by photoluminescence-excitation (PLE) and photoluminescence (PL) spectroscopy to get insight into the nature and electronic structure of this color center. We have demonstrated that the large frequency defect (difference between oscillation frequencies in the ground and excited electronic states) does bring about large discrepancy between PLE and PL spectra and comparatively high isotopic shift of the zero phonon line. Both effects seem to be rather common to split-vacancy centers (for example, where the frequency defect reaches record high values. Isotopic substitution of carbon atoms in the diamond lattice results in even larger shifts, which are only partially accounted for by a redistribution of electron density caused by the volume change of the diamond lattice. It was shown that the vibronic frequency in this case does not depend on the mass of carbon atoms. The greatest part of this isotopic shift is due to anharmonicity effects, which constitute a substantial part of vibronic frequency observed in this center. The exact physical mechanism, which leads to significant enhancement of anharmonicity on substitution ofto, is yet to be clarified.