Disentangling the conductivity spectra of two-dimensional organic conductors

The optical spectrum of a κκ-phase organic conductor is thoroughly analyzed for the example of κ-(BEDT-TTF)2Cu[N(CN)2]Br0.85Cl0.15κ-(BEDT-TTF)2Cu[N(CN)2]Br0.85Cl0.15 in order to identify its various contributions. It is shown how the complex spectra can be decomposed using different approaches; the intradimer and interdimer contributions are discussed. In particular the fingerprints of electronic correlations in these spectra are considered.