Liquid-crystal phase transition probed by fluorescent molecules

Phase transition of four liquid crystal materials have been studied by meas uring the decay times of time-resolved intensity of fluorescence from two k ind of dyes, malachite green and cryptocyanine, doped in these materials. I t was found that the observed fluorescence lifetimes observed depend strong ly on the doped molecules and that they change depending on the phase trans ition of the liquid-crystal materials. These results show that the fluoresc ence lifetime measurements are effective molecular probes for estimating th e microscopic dynamics in these materials.