抄録
Far-infrared spectra of quinolinium-(TCNQ)2, bipyridinium-(TCNQ)2, 4-amino-2,3,5,6-tetramethyl anilinium-(TCNQ)2, cobalticinium-(TCNQ)2, triethylammonium-(TCNQ)2, lithium-(TCNQ) and TCNQ alone were observed at room temperature. The absorption peaks of the spectra were discovered at 296 cm−1 for all TCNQ salts. The absorption edges were found at about 40 cm−1 for all samples except Li(TCNQ) alone. The intensity change in the vicinity of the edges varied in parallel with the electrical conductivity at room temperature. These edges are interpreted as due to the direct allowed transition from a ground state to an excited band on the basis of the fact that the absorption coefficient k is proportional to (ν−νG)1⁄2. Here ν shows the wave-number of incident light and νG is a constant. Three absorption lines were found at 219 cm−1, 143 cm−1, and 114 cm−1 in the TCNQ spectra.
A model, in which the excited band is a conduction band, seems to provide a consistent explanation of the temperature dependence of the electrical conductivity. The temperature dependence of the magnetic susceptibilities is also discussed.
