Polarized photoluminescence and measurement of degree of order in mixed oriented polymer liquid crystal films

Optical anisotropy in a new form of cross-linked liquid crystal network incorporating a fluorescent chromophore has been demonstrated. Linearly polarized absorption and fluorescence is observed in oriented thin films. From measurement of absorption and fluorescence anisotropy, the order parameter was found to be 0.65 and 0.80 respectively. Temperature dependent birefringence measurements reveal that there is no appreciable loss of alignment up to 200°C. Raman spectroscopy was used to investigate the discrepancy between the absorption and fluorescence measurements. It is found that the fluorescent chromophore is less well ordered than the liquid crystal. The reasons for this are discussed.