Optical properties of the organic metal (BEDT-TTF)4[Ni(dto)2]

(BEDT-TTF) 4 [Ni(dto) 2 ] was investigated from 0.3 cm -1 to 8000 cm -1 with various optical techniques. On the background that quantum oscillation experiments are in good agreement with band structure calculations, the optical properties show some surprising aspects. While the MIR spectra are similar to those of other metallic BEDT-TTF materials, a sharp pseudo-gap feature and a very narrow Drude peak develop in the FIR at low temperatures.