LOW-TEMPERATURE REFLECTION SPECTRUM OF K-TCNQ SINGLE-CRYSTAL

Polarized reflection spectra of a K-TCNQ single crystal have been measured at 27,295 and 413 K. The absorption spectra were derived from the observed reflection spectra by Kramers-Kronig transformation. At 27 K, the near-infrared absorption band which is associated with the charged transfer between TCNQ- ions, splits into a strong sharp peak at 8 × 103 cm-1 and a weak broad band at 11 × 103 cm-1. These bands were interpreted in terms of the strongly correlated extended Hubbard model including the nearest-neighbor Coulomb interaction. © 1979.