What are the different types of spectrometers used in fluorometry?

There are several different types of spectrometers utilized in fluorometry. One type is a filter fluorometer, in which light passes through filters. This fluorometer creates specific emission and excitation wavelengths by utilizing optical filters. The filter blocks external wavelengths however it transmits wavelengths associated with the compound. The light then passes through the sample to be measured, and a specific wavelength is absorbed while a longer wavelength becomes emitted; the emitted light is measured by a detector. One can also change the optical filter for different substances to be measured. Filter fluorometers are typically used in experiments that consistently measure different substances since optical filters are cost-efficient and easy to use.   

Spectrofluorometers are another type of spectrophotometer used in fluorometry; light passes through diffraction grating monochromators. Spectrofluorometers detect and measure the fluorescence of an analyte in a sample based on its specific emission and excitation wavelengths. A specific wavelength becomes selected and the emission is observed either on a single wavelength or an emission spectrum. The level of fluorescence is correlated to the concentration level of the analyte in the sample.  

A third type of fluorometer is laser-induced fluorescence, in which an atom or molecule is excited to a higher energy level by absorption of light where it subsequently is captured by a photodetector. LIF is used for detection of selective species and flow visualization, studying structure of molecules and measurements. The wavelength selected is typically at which the species has its most abundant cross section. The excited species escalates and emits light a wavelength longer than the excitation wavelength. The emitted light is recorded with a PMT or filtered photodiodes.