We have explored pure FLC and fluorescent dye doped system using
dielectric study, UV absorption and fluorescence studies. In this study we found that UV absorption is higher for fluorescent dye doped system
in comparison to the pure system. The excitation and emission wavelengths
along with quantum yield have been evaluated for all the mixtures
from fluorescence study. The excitation wavelength of
fluorescent dye doped system has been shifted toward a higher side in
comparison to the excitation wavelength of fluorescent dye i.e.
260 nm. The dielectric study suggests that mixture 2 is an optimum concentration
of fluorescent dye in pure FLC therefore, after this mixture
there is saturation or slightly changes in the value of dielectric parameters.
The enhancement in relative permittivity for fluorescent dye doped
system is an indication of better alignment due to the supportive nature
of dipole moment of fluorescent dye molecules and dipole moment of
FLC molecules. The relaxation frequency with temperature curve also
shows that there exists an optimum concentration of fluorescent dye
i.e. mixture 2 for which the value of relaxation frequency is highest
and after this concentration there is decrement in the value of relaxation
frequency. The nature of relaxation frequency curve of fluorescent dye
doped system follows the same trend as for pure FLC which indicates
that relaxation frequency ruled out any chemical reaction between
dye and FLC molecules. The frequency behavior of tanδ shows that relaxation
process is due to Goldstone mode which is associated with
phase fluctuation of FLC molecules.