Spectral investigations of organic metals β″-(BEDT-TTF)4A[M(C2O4)3]·DMF, where A = NH4+, K+ and M = CrIII, FeIII

Spectral investigations of the new isostructural organic metals of the formula β″-(BEDT-TTF)4A[M(C2O4)3]·DMF, where A = NH4+, K+ and M = CrIII, FeIII, were performed. The polarized reflectance spectra of single crystals of these salts were recorded in the range 600-6500 cm−1. Additionally, the optical absorption spectra of the powdered salts dispersed in KBr pellets, in the range 200-40,000 cm−1 were measured. The spectra are characteristic for organic metals and show small anisotropy as typical for quasi-two-dimensional (2D) materials. A Kramers-Krönig analysis of the reflectance data was performed to obtain the optical conductivity spectra. The frequency dependences of the reflectivity were fitted with the Drude or Drude-Lorentz models and the transport parameters were evaluated.