Optical properties of N-propylquinolinium(TCNQ)2 through the phase transition

Abstract

We have investigated the infrared and optical reflectivity of a single crystal of Npropylquinolinium( TCNQ)2, a salt containing TCNQ tetramers. For light polarized along the chain axis, the spectra show a change below the 220 K phase transition: the vibrational lines split into doublets. These findings are in contradiction with the crystal structure, where tetramers become more uniform upon cooling and no intermolecular charge redistribution is found