Fluorescence Detection 

 

•As the fluorescent molecule present in or on the particle is interrogated by the laser light, it will absorb energy from the laser light and get in excitation phase.

•After the peak it releases the absorbed energy by emission of photons of a longer wavelength than the excitation wavelength as fluorescence

•The difference between wavelengths of the emission and excitation maxima is called the Stokes shift.

These photons of light are steered and collected by optical lens and filters at specific wavelengths.

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Figure 1. Absorption takes place at higher energy (shorter wavelength) than fluorescent emission at lower energy (longer wavelength)