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The “destructive” fermi resonance
Author(s) -
Chisler E. V.,
Davydov V. Yu.,
Goncharuk I. N.,
Ivanova E. A.
Publication year - 1977
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2220790137
Subject(s) - fermi resonance , raman spectroscopy , brillouin zone , resonance (particle physics) , coupling (piping) , atomic physics , vibration , fermi gamma ray space telescope , chemistry , crystal (programming language) , spectral line , infrared , molecular physics , physics , condensed matter physics , nuclear magnetic resonance , optics , materials science , quantum mechanics , metallurgy , computer science , programming language
Abstract For the first time the coupling between the fundamental vibration of a crystal and its second‐order vibrational spectrum is observed which causes, due to the interference of the transition probabilities, the decrease of the intensity of second‐order vibrational spectrum and, in certain cases, its almost full cancellation. The “destructive” Fermi resonance is revealed in the Raman and infrared spectra of sodium nitrite. The energy of the resonance coupling and the unperturbed transition probabilities are calculated. The spectroscopic data show, that the electrooptic parameters of the second‐order vibrations and the energy of their interaction with the fundamental vibration are approximately independent of the wave vector within the Brillouin zone.