Vladimir State Universitynamed after A.G. and N.G. Stoletovs, 600000 Vladimir, Russia
2 E.K. Zavoisky Physical-Technical Institute – Subdivision of the Federal Research Center «Kazan Scientific Center of Russian Academy of Sciences», 420029 Kazan, Russia
3 Institute for Spectroscopy RAS, 108840 Moscow, Troitsk, Russia
4 Moscow State Pedagogical University, 119991 Moscow, Russia
Published online: 25 October 2019
This article has no abstract.
© The Authors, published by EDP Sciences, 2019
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