Abstract
A substantially complete and definite interpretation of Cs2 TCNQ3 infrared and Raman spectra (in the region of intramolecular modes) is achieved. The presence of vibronic absorptions in the infrared spectra is quantitatively accounted for in terms of a newly introduced model of electron-molecular vibration (e-mv) interaction, which takes into consideration the coupling with both the intra- and inter-trimer charge transfer transitions. The same model, with the same parameters, is also able to explain the so far unrecognized e-mv perturbation (frequency shift) of the Raman active totally symmetric modes. The re-examination of the Cs2 TCNQ3 optical spectra thus shows that the electronic charge on the Cs2 TCNQ3 molecular sites differs appreciably from zero and one, being 0.14 and 0.93 for centric and non-centric TCNQ molecules, respectively.