Fluorescence and Fluorescence Excitation Spectroscopy

The powerful technique of fluorescence excitation significantly enhances the capabilities of conventional fluorescence spectroscopy, which offers insights into chemical composition of the examined specimens. In a conventional fluorescence measurement the excitation wavelength is fixed and the detection wavelength varies, while in a fluorescence excitation measurement the detection wavelength is fixed and the excitation wavelength is varied across a region of interest. This very important capability makes it possible to produce an excitation/emission matrix that fully characterises the sample in a matter of minutes. This is in contrast, with fluorescence at a single excitation wavelength or with wide band excitation (such as in a fluorescence microscope) which provides only partial information. Importantly, the fluorescence excitation spectra contain information that is complementary to the fluorescence spectra. This facility is of importance in many biological applications, where the objective is frequently to make a fine distinction between two parts of a specimen with broad and very similar fluorescence curves. Applications of fluorescence excitation are as diverse as those of fluorescence and specimens can be examined rapidly and non-destructively.