Atomic Fluorescence Spectrum:

You know in which an atom holds a set of quantised energy levels which could be occupied through the electrons depending on the energy. The atoms acquired through the process of atomisation in a low temperature flame are primarily within the ground state. While exposed to an intense radiation source consisting of radiation which could be absorbed through the atoms, these get excited. The source could be a continuous source such as xenon lamp or a line source like a, electrode less discharge lamp, hollow cathode lamp or a tuned laser. A radiationally excited atom relaxes back to the ground state accompanied through a radiation. This phenomenon is known as atomic fluorescence emission. The radiative excitation and de-excitation procedures for analytical AFS measurements are in the UV- VIS range. The intensity of emitted light is measured along with the help of a detector that is placed within a direction perpendicular to in which of incident radiation and absorption cell.

The plot of the measured radiation intensity as a function of the wavelength constitutes atomic fluorescence spectrum and creates the basis of analytical fluorescence spectrometric methods.

In place of the flame, a graphite furnace could be employed for conversion of the analyte within gaseous atoms in the ground state. A graphite furnace atom cell combined along with a laser radiation source can gives the detection limits in the range of femtogram (10^-15) to attogram (10 ^-18) that is quite promising.