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Pressure‐induced Fermi resonance between fundamental modes in 7,7,8,8‐tetracyanoquinodimethane
Author(s) -
Sun Chenglin,
Zhao Hongliang,
Liu Chunyu,
Zhou Mi
Publication year - 2017
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.5191
Subject(s) - fermi resonance , anharmonicity , tetracyanoquinodimethane , resonance (particle physics) , chemistry , coupling (piping) , raman spectroscopy , fermi gamma ray space telescope , fermi level , condensed matter physics , molecular physics , nuclear magnetic resonance , atomic physics , materials science , physics , optics , molecule , quantum mechanics , organic chemistry , metallurgy , electron
Herein, in‐situ high pressure Raman spectra of 7,7,8,8‐tetracyanoquinodimethane (TCNQ) have been measured up to 10 GPa, and a first‐order phase transition was detected at about 2.3 GPa. An anharmonic coupling (Fermi resonance) between fundamental modes was observed. The relationship of Fermi resonance parameters (intensity ratio, coupling coefficient, frequency separation and frequency separation of unperturbed transition) with pressure was discussed. The frequency separation dominated the decay of the intensity ratio of Fermi resonance doublets, and this would be another character of anharmonic coupling between fundamental modes. Copyright © 2017 John Wiley & Sons, Ltd.