Simulated time-resolved fluorescence in ordered phases.

An interpretation of time resolved fluorescence emission experiments, performed on probes in isotropic and ordered polar phases, is developed. The system under scrutiny is provided by a dipolar molecule undergoing rotational diffusion, whose dipole moment is coupled to a stochastic reaction field generated by the ordered polar medium. Under quite general conditions, the fluorescence emission is defined as an integral over all possible orientations of the ground and excited states. Since the model allows to reproduce experimental results at a semi-quantitative level and a negligible computational cost, a user-friendly package with graphics utilities has been created, which can be of help to investigate interactively the dependence of the simulated spectra upon several macroscopical parameters such as the dielectric constants and the viscosity of the medium.