Excitation spectrum, ultraviolet-visible fluorescence spectroscopy

Analytical absorption spectroscopy in the ultraviolet and visible regions of the elechomagnetic spectrum has been widely used in pharmaceutical and biomedical analysis for quantitative purposes and, with certain limitations, for the characterisation of drugs, impurities, metabolites, and related substances. By contrast, luminescence methods, and fluorescence spectroscopy in particular, have been less widely exploited, despite the undoubted advantages of greater specificity and sensitivity commonly observed for fluorescent species. However, the wider availability of spectrofluorimeters capable of presenting corrected excitation and emission spectra, coupled with the fact that reliable fluorogenic reactions now permit non-fluorescent species to be examined fluorimetrically, has led to a renaissance of interest in fluorimetric methods in biomedical analysis. 

One interesting development in the Raman spectroscopy of catalysts has been the use of an ultraviolet laser to excite the sample. This has two major advantages (1) the scattering cross-section, which varies with the fourth power of the frequency, is substantially increased and (2) the Raman peaks shift out of the visible region of the spectrum where fluorescence occurs. The interested reader is... 

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