Time-resolved polarized fluorescence spectroscopy of photoreactive systems in uniaxially organized molecular media

A description of the time-resolved polarized fluorescence spectroscopy on photoreactive systems incorporated into a uniaxially organized molecular medium is discussed. The treatment assumes many-ground-state species interconverting in the excited states. The ground- and excited-state species undergo different solute-matrix aligning interactions. The rotational motion of the excited-state species is state-dependent. The diffusion model in the state-dependent potential for asymmetric and symmetric rotors is considered. Expressions enabling the computation of polarized fluorescence decays are derived and discussed. The case when the state-to-state kinetics of the systems are controlled by fluorophore-matrix aligning interactions and rotational dynamics of the fluorophores is considered. Some possible experimental arrangements enabling studies of such molecular systems as monolayers, bilayers, membranes as well as solid/air and liquid/air surfaces, are briefly considered. Indicated is a possible application of the theoretical and experimental methods discussed in this work to the time-resolved polarized total internal reflection fluorescence spectroscopy of thin layers of different kinds of molecular assemblies at solid/liquid and liquid/liquid interfaces.