Principle of Atomic Fluorescence Spectrometry:

Atomic fluorescence spectrometry is the analytical techniques based on optical emission from gas-phase atoms which have been excited to higher energy levels through absorption of radiation. It incorporates aspects of both absorption and emission of radiation. Within atomic fluorescence spectrometry the analyte is brought within an atom reservoir that could be a flame, plasma, glow discharge, or a furnace and is excited through focusing a beam of monochromatic electromagnetic radiation emitted through an appropriate primary source. The radiation source could be of a continuous kind such as xenon lamp or a line source. Hollow cathode lamp (HCL), electrodeless discharge lamp (EDL) or tuned lasers are the generally employed line sources.

In addition of looking at the amount of light absorbed within the procedure, we focus our attention to the fluorescence emission resulting from the relaxation of the excited atoms. Same to the molecular fluorescence, the atomic fluorescence is also measured within a direction perpendicular to the direction of exciting radiation. The fluorescence radiation emitted from the excited species is measured along with or without being spectrally resolved.

Since you have learnt above, the fluorescence emission might be of the similar wavelength that is resonance fluorescence or of a different wavelength because of other fluorescence mechanisms. Again, every element has own features atomic fluorescence spectrum. The location of the fluorescence emission signal denotes the identity of the analyte whereas the intensity is a measure of its concentration. The intensity of the 'fluorescence' increases along with increasing atom concentration in the flame, giving the basis for its quantitative determination.

It is found in which the atomic fluorescence intensity is associated to the exciting light source and the radiating intensity, besides the concentration of a few of the elements within the sample to be determined.