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)… Click to show full abstract
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.
               
Click one of the above tabs to view related content.