Sources:
As described earlier, the fluorescence power or intensity, IF, is straight proportional to the source power, P0. An increase in P0 will generate a larger signal for a given concentration and thus improve sensitivity. However, the source must be more intense than which needed for UV-VIS absorption spectroscopy. The tungsten filament and deuterium lamps used in absorption spectrophotometers are commonly not appropriate for fluorescence instruments as they lack the desired intensity. As molecular absorption spectra commonly are broad, a highly monochromatic source is commonly not needed; an intense continuum source that emits throughout the UV, visible, and near infrared regions is adequate. Thus, in fluorescence measurements a source along with intense emission lines at certain frequencies are desirable.