The Fano anti-resonance and IR-properties of organic conductors

At high temperatures, i.e. in the metallic state excitation of the IR-forbidden symmetric intramolecular modes is shown to become effective. Near the threshold of emission for such a phonon there appears a fine structure as a result of the acoustic phonon assisted excitation of the intramolecular mode by energetic band electrons. The absorption reveals the behaviour typical of the Fano anti-resonance. The infrared frequency dependence of the organic compounds conductivity is discussed.