TAILIEUCHUNG - Vibrational anharmonicity of A-band related optical center and its temperature dependence studied by femtosecond laser excitation in bulk natural diamond

The derived temperature dependences of the peak intensities, separations and half-widths of the separate spectral peaks in the A-band phonon progressions indicate the different trends for vibration-free zero-phonon electronic transition and vibration-related lower-energy electronic transitions to high vibrational levels of the ground electronic state – lower thermal damping and more softened phonon for the zero-phonon transition, also implying the extended defect origin of the A-band photoluminescence. | Communications in Physics Vol. 34 No. 1 2024 pp. 1-10 DOI https 0868-3166 19292 Vibrational anharmonicity of A-band related optical center and its temperature dependence studied by femtosecond laser excitation in bulk natural diamond Sergey Kudryashov Pavel Danilov Nikita Smirnov Volodymyr Kovalov Lebedev Physical Institute Russian Academy of Sciences 53 Leninsky prospect 119991 Moscow Russia E-mail kudryashovsi@ Received 28 October 2023 Accepted for publication 30 December 2023 Published 15 March 2024 Abstract. Unusual A-band spectra with well-resolved quasi-periodical phonon progressions of multiple peaks N 9 were excited in a natural diamond by 515 nm 300-fs laser pulses at vari- able pre-heating temperatures of 24-200 C. The non-radiative multi-phonon part of the relax- ation path was comparable with the total relaxation energy zero-phonon line energy pointing out some extended defects . dislocations as the recombination centers of the A-band emis- sion. The derived temperature dependences of the peak intensities separations and half-widths of the separate spectral peaks in the A-band phonon progressions indicate the different trends for vibration-free zero-phonon electronic transition and vibration-related lower-energy electronic transitions to high vibrational levels of the ground electronic state lower thermal damping and more softened phonon for the zero-phonon transition also implying the extended defect origin of the A-band photoluminescence. Keywords natural diamond A-band femtosecond laser photoluminescence temperature effect dislocations. Classification numbers . 1. Introduction Photoluminescence is the most sensitive spectroscopic method for characterization of in- trinsic non-equilibrium carriers interstitial-vacancy pairs 1 and extrinsic impurity atoms or clusters 2 imperfections in the ultra-hard regular diamond lattice. Optically-active impurity 2024 Vietnam Academy of Science and Technology

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• Natural diamond
• Temperature effect
• Lower energy electronic transitions
• A band photoluminescence
• Zero phonon line energy
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