Fluorophores

Fluorescence probes represent the most important area of fluorescence spectroscopy. One can spend a great deal of time describing the instrumentation for fluorescence spectroscopy, including light sources, monochromators, lasers, and detectors. However, in the final analysis, the wavelength and time resolution required of the instruments are determined by the spectral properties of the fluorophores. Furthermore, the information available from the experiments is determined by the properties of the probes. Only probes with nonzero anisotropies can be used to measure rotational diffusion, and the lifetime of the fluorophore must be comparable to the correlation time of interest. Only probes which are sensitive to pH can be used to measure pH. And only probes with reasonably long excitation and emission wavelengths can be used with tissues which display autofluorescence at short excitation wavelengths.