Atomic emission spectrometry:
In atomic emission spectrometry (AES), a reproducible and representative amount of the sample is introduced into an atomization-excitation source where it is converted into atomic vapours of the analyte in excited state. In the atomisation-excitation source the analyte undergoes a number of processes to be atomised and then get excited. As the excited state is short lived, an excited atoms return back to the ground state accompanied through the emission of electromagnetic radiation which is characteristic of the constituents of the sample. An AES is a versatile technique because of the availability of a huge range of atomisation-excitation sources.
Plasma is a high energy source which is an electrically neutral conducting gaseous mixture having a significant concentration of cations and electrons. As an electrical conductor it can be heated inductively by coupling with an oscillating magnetic field. The temperature of the plasma may be of the sequence of 5,000 to 8,000 K.
In the ICP-AES the analyte sample is introduced into the centre of the plasma as an aerosol with the help of a nebuliser using argon flow. As the energy of the plasma source is quite high it ensures the excitation of the atoms of all the elements present in the sample which then relax by emitting EM radiation of characteristic wavelengths of different elements. Thus, it is a multi element technique.