Polarized IR reflectance studies of the organic superconductor (BEDO-TTF)2ReO4(H2O)

Polarized reflectance spectra of single crystals of (BEDO-TTF)2ReO4(H2O) (BEDO-TTF, bis(ethylenedioxy)tetrathiafulvalene were measured at room temperature over the spectral range 500–8300 cm−1. The incident radiation was polarized parallel and perpendicular to the stacking axis of the donor molecules. By fitting a Drude model to the dispersion of reflectance the Drude parameters were obtained and, starting from the plasma frequency, the bandwidth 4t of the electronic system was derived. The real part of the dielectric function and the optical conductivity were determined by a Kramers-Kronig transformation. Both the optical conductivity and the bandwidth 4t are compared with values obtained by a band-structure calculation. In the frequency region below 2000 cm−1 the origin of the vibrational transitions is discussed and compared to transmission measurements of optical density.