Orientational order and dynamics of fluorescent probes in aligned lyotropic phases by fluorescence depolarization spectroscopy. Perylene in a nematic discotic phase. A comparison with2H NMR

The orientational order and dynamics of perylene in the nematic discotic phase (NdII) of the potassium laurate/KCl/decanol/water system has been investigated by fluorescence depolarization (FD) spectroscopy. The order parameters of perylene-d 12 in the same phase had been previously determined by 2H NMR. FD experiments were performed with the phase-modulation technique in the temperature range between 10°C and 50°C. At each temperature we could determine and for the axis of the transition moments of perylene, together with the rotational correlation time ΘR. All these quantities assume reasonable values and show regular trends as functions of temperature. In particular, is in good agreement with that determined by 2H NMR.