Ultraviolet to far infrared optical properties of the one-dimensional conductor K2Pt(CN)4Br0·3. 3H2O

An experimental study of the optical properties of single crystals of the quasi-one-dimensional conductor K₂Pt(CN)₄Br_0·3, 3H₂O in the spectral range from 45,000 to 10 cm^?1 is presented.For light polarized perpendicular to the highly conducting direction the material behaves as a transparent dielectric, as evidenced by reflection and transmission spectra. The reflection spectrum measured with polarization parallel to the chain direction (E∥Z) shows, in addition to the previously reported ‘metal-like’ optical reflectance and plasma edge in the visible, deviations from free carrier type reflectance in the i.r. This was expected because the conductivity is thermally activated at low temperatures. The optical constants for E∥Z polarization have been determined by Kramers-Kronig analysis of the reflection spectrum and, at a few discrete wavelengths, from measurements of polarized reflectance under oblique incidence. The results are qualitatively consistent with various models of the electronic structure but do not distinguish between them.