  A detailed investigation of the charge-ordered charge-transfer salt
\delta-(EDT-TTF-CONMe$_{2}$)$_{2}$Br by thermal-expansion measurements and
dielectric spectroscopy reveals three dynamic processes of relaxational
character. The slowest one exhibits the characteristics of glassy freezing and
is ascribed to the conformational dynamics of terminal ethylene groups of the
organic molecules. Such a process was previously found for related
charge-transfer salts where, however, the anions form polymerlike chains, in
contrast to the spherical anions of the present material. Dielectric
spectroscopy reveals two additional relaxational processes. The characteristics
of the faster one are consistent with excitations of a one-dimensional Wigner
lattice as recently observed in this material by infrared spectroscopy, which
are also accompanied by conformational changes of the molecules. However, at
low temperature the ethylene-group relaxation exhibits the
cooperativity-induced dramatic slowing down that is typical for glassy
freezing, while the defect-related Wigner-lattice excitation follows thermally
activated behavior as expected for single-dipole relaxations.
