Time-correlated photon counting: Differential methods applied to anisotropy decay

摘要

A method is described that makes it possible to measure luminescence decays for both parallel and perpendicular excitation geometries in a single experimental run. The rotational diffusion of oxazine 725 in five solvents of different viscosities is characterized using the new procedure. The measurements are challenging in that the rotational diffusion times are close to the excited state lifetime. The advantage of the new procedure lies in the increased confidence that comes with measuring both polarizations under the same conditions. The same principle is applicable in any circumstance involving the comparison of two or more samples.