From Wikipedia, the free encyclopedia - View original article

Jump to: navigation, search

Atomization or atomizer may refer to:

In science and technology

As places

in the arts

Atomization in optical atomic spectroscopy[edit]

The difference between a spectrometer or spectrophotometer for atomic absorption or molecular absorption is the need to convert the analyte solution into free atoms. The process of converting an analyte in solid, liquid or solution form to a free gaseous atom is called 'atomization'.

There are two methods for atomization; flame atomization and electrothermal atomization.

In flame atomization, a liquid sample is first passed through a nebulizer to convert the sample into a fine mist while a solid sample can be directly inserted into the flame.The nebulized, liquid sample is aspirated into a spray chamber by passing a high pressure stream consisting of one or more combustion gases which are passed at the end of the capillary tube immersed in the sample.The impact of the sample with a glass impact bead produces an aerosol mist.The aerosol mist mixes with combust gases in the spray chamber before passing to the burner, where the flame thermal energy desolvates the aerosol mist towards dry aerosol particles.Subsequently, the thermal energy volatiles the particles producing the vapours consisting of molecular and ionic species and free atoms.

With flame atomization, the liquid sample is aspirated into the flame by the venturi effect of the combustion gases flowing through the burner. The flow of sample into the flame is typically in the range of several milliliters per minute. For this reason, flame Atomic Absorption (AA) requires milliliter-sized samples. With furnace atomization, a microliter-sized portion of sample is pipette into a small, open-ended graphite cylinder, which is located in the light beam of the instrument, and the cylinder is then heated by applying a high electrical potential across the cylinder. The vapor cloud thus produced is contained within the cylinder. The result of this method of heating is not only the consumption of much less sample, but the generation of a much more concentrated sample vapor, which translates to much higher sensitivity. The drawbacks of this technology (electro thermal atomization) as currently practiced is that it is more expensive (due mainly to the cost of the graphite tubes), and takes significantly longer to perform an analysis than with flame atomization (minutes versus seconds), and the graphite tubes, which must be replaced relatively frequently, are expensive.

Flame atomization is used for the Optical Atomic Spectroscopy methods of Atomic Absorption (AA), Atomic Fluorescence (AF), and Atomic Emission (AS). Flame atomization is the most common atomization method and is most reproducible of all liquid-sample introduction methods for AA and AF.

A major difference between electrothermal and flame atomization methods is that in 'electro thermal atomization', the atom cloud is released into a relatively small volume of gas, while in contrast, in flame atomization, the atom cloud is diluted by the high flow rate of gases and by expansion of gases during combustion;

See also[edit]