13C NMR study of partially deuterated κ-(BEDT-TTF)2Cu[N(CN)2]Br

Synthesis of deuterated and 13C-enriched BEDT-TTF, and the results of 13C NMR (nuclear magnetic resonance) measurement of κ-(BEDT-TTF)2Cu[N(CN)2]Br salt are reported where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene. We synthesized the BEDT-TTF molecule 13C-enriched on only one side of the central carbon sites. By using this molecule, we could avoid the Pake doublet and estimate the density of states from the Knight-shift and the spin–lattice relaxation rate. The reduced mass effect predicted from the specific heat measurement was not observed in the 13C NMR measurement.