Mechanism of conduction in TTF and TMTSF organic conductors from a study of their vibrational spectra

The charge transfer complexes of organic donors TTF and TMTSF have been prepared and studied with infrared spectroscopy. The nature of transition has been studied by analyzing features of absorption. TTF-TCNQ was found to be a Peierls semiconductor and not metallic. This shows that the mean field transition temperature is operative in TTF-TCNQ. TMTSF-TCNQ and TMTSF-DDQ showed lesser band gap than that of TTF-TCNQ. TTF-DDQ and TTF-I₂ also showed very small band gap and were more conducting than TTF-TCNQ. The band gaps could be assigned to either the Peierls gap or the pinning gap of charge density waves.