Time-resolved
fluorescence measurements reveal significantly more information about the
examined processes that the steady-state studies. Real-world specimens, such as
biological objects may present similar fluorescence spectra lacking distinctive
structure, but very complex and widely differing fluorescence lifetime decays.
The lifetimes can be treated as optical signatures of different chemical
composition. They can then be used to distinguish the different compounds that
give similar fluorescence spectra or to help identify the molecules by
comparing to the known standards.
The knowledge of the decay curves detected at a number of wavelengths within a certain range makes it possible to obtain the time-resolved spectra. This powerful approach may be used to enhance a weak signal of interest compared to a strong background signal. Currently, lifetime techniques are applied to diverse fields of study including semiconductors, photochemistry, biology, molecular biophysics, polymers and many others.