| The rotational dynamics of single 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4 H-pyran (DCM) chromophores isolated in a thin poly(methyl acrylate) (PMA) film in the presence of an external electric field are studied using confocal fluorescence microscopy. The rotational dynamics are found to be weakly perturbed by a 50 V/mum electric field, a typical field strength used in processing electro-optic polymer-composite materials. The expected perturbation of the rotational dynamics based on statistical mechanics is derived, and is consistent with the alignment potential created by the electric field and the thermal energy available to DCM. Comparative studies of Rhodamine B and DCM rotational dynamics are presented. The rotational dynamics are found to be non-exponential, consistent with previous studies suggesting that the dynamical heterogeneity of the polymer environment influences chromophore reorientation. The temperature-dependent blinking dynamics of violamine R (VR) in poly(vinyl alcohol) are presented. The VR blinking dynamics demonstrate power-law behavior consistent with the population and depopulation kinetics for the non-emissive state being dispersed. Interestingly, the power-law exponent for the off times is temperature invariant, while the on-time exponent demonstrates weak temperature dependence. This result is discussed in the context of electron-transfer models for the production and decay of the non-emissive state. |
