TY - JOUR

T1 - Anharmonicity effects in impurity-vacancy centers in diamond revealed by isotopic shifts and optical measurements

AU - Ekimov, E. A.

AU - Krivobok, V. S.

AU - Lyapin, S. G.

AU - Sherin, P. S.

AU - Gavva, V. A.

AU - Kondrin, M. V.

PY - 2017/3/15

Y1 - 2017/3/15

N2 - We studied isotopically enriched nano- and microdiamonds with optically active GeV- centers 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 SiV-), 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 of C12 to C13, is yet to be clarified.

AB - We studied isotopically enriched nano- and microdiamonds with optically active GeV- centers 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 SiV-), 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 of C12 to C13, is yet to be clarified.

KW - HIGH-PRESSURE

KW - COLOR-CENTER

KW - ABSORPTION

KW - GERMANIUM

KW - SPECTRA

KW - DEFECTS

UR - http://www.scopus.com/inward/record.url?scp=85016031882&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.95.094113

DO - 10.1103/PhysRevB.95.094113

M3 - Article

AN - SCOPUS:85016031882

VL - 95

JO - Physical Review B

JF - Physical Review B

SN - 2469-9950

IS - 9

M1 - 094113

ER -