DIELECTRIC-RELAXATION IN 2-1 CHARGE-TRANSFER COMPLEXES OF 2,3,7,8-TETRAMETHOXYCHALCOGENANTHRENES AND TETRACYANOETHENE

The dielectric behaviour of 2: 1 charge-transfer complexes of the 2,3,7,8-tetramethoxychalcogenanthenes (5,10-dichalcogenacyclodiveratrylenes) Vn2EE' (E = E' = S, Se; E = S, E' = Se) with tetracyanoethene (TCNE) is studied by conventional a.c. measurements and by the thermostimulated depolarization current (TSCD) technique as an alternative experimental method. In the low-frequency side of the dielectric loss curves (epsilon" vs. frequency plots) the relaxation peaks of the compounds are hidden by a continuous increase in dielectric loss. By a transformation of complex permittivity epsilon* = epsilon' - i-epsilon" into complex polarizability alpha* = alpha' - i-alpha" the loss peaks can be seen in the alpha" vs. frequency plots. The existence of these relaxations is confirmed by TSDC measurements.