Atomization

The conversion of atoms into discrete atoms is called atomization. The flame atomization processes are complex. The production of free atoms must take place in the few milliseconds that correspond to the upward movement of the molecules and atoms through the flame gases. The atomization step must convert the analyte within the aerosol (discrete atoms) into free analyte atoms for Atomic absorption spectroscopy Flame atomic-emission spectrometry.

 For Atomic absorption spectroscopy, the following sequence of events occurs in rapid succession.

Ø Desolvation of the aerosol

 The water or any other solvent used in the sample becomes vaporized and it leaves minute particles of dry salt.

Ø Vaporization of the resulting particles

 At the high temperature of the flame, the dry salt is vaporized (converted to gaseous molecules).

Ø Dissociation of gaseous molecules

 The gaseous molecules are dissociated to give neutral atoms.

For Flame atomic Emission these two more events must occur,

Ø Excitation of atoms or molecules

The neutral metal atoms are excited by the thermal energy of the flame. (Excitation occurs in AAS by thermal collisions as well as by absorption of radiation from the light source.)

Ø Emission

 From the excited electronic level(s) of the atom, a reversion takes place to the ground electronic state with the emission of light whose wavelength is characteristic of the element and whose intensity is proportional to the amount of analyte element present.

Types of Atomizer

The instrument used for the process of atomization is called the atomizer. There are two main types of atomizers:

Continuous Atomizer	Discrete Atomizer
It steadily introduces the analyte.	It introduces the analyte discontinuously.
This process is nonstop.	Small fractions are introduced gradually in this process.
E.g. Flame Atomizer	E.g. Electro thermal atomizer.