H-1-NMR AND C-13-NMR IN THE ORGANIC CONDUCTOR DMTM(TCNQ)2

The electronic and dynamic changes at the phase transition at T(c) = 2 72 K in the quasi one-dimensional organic conductor DMTM(TCNQ)2 have b een investigated with H-1- and C-13-NMR on powder samples and single c rystals. The TCNQ hyperfine coupling constants were calculated from th e observed H-1- and C-13-Knight shift, and the charge redistribution a t T(c) is determined by the C-13 single crystal measurements, The DMTM cation dynamics have been studied with broadline H-1-NMR which indica tes a slowing down of cation motion at T(c) as evidenced by the temper ature dependence of the relaxation rates. The results support a tentat ive explanation of the unusual phase transition, an ''inverted Peierls '' transition, given by Visser et al. [1, 2].