Wavelength Selectors use in Atomic Absorption Spectroscopy

 Wavelength Selectors

A wavelength selector allows a specific bandwidth to pass through it. The sample absorbs a certain wavelength.

In atomic absorption spectroscopy a narrow band of wavelengths increase and improved the sensitivity of an experiment. Its detectability is also improved when the transmission is high.

There are several types of wavelength selectors.

·        Filters

·        Grating monochromators

·        Prism monochromators.

1) Filters

Filters select a specific wavelength that allows narrow bandwidths of radiation to pass through it. They are divided into three following categories:

Absorption Fiters

These filters absorb polychromatic wavelength and transmit only a single and specific band of wavelengths.

They are inexpensive, available and can be as simple as colored glass sheet, plastics or gelatin material.

It results about 10-20% specified wavelength to pass through the absorption filters.

Absorption filters only allow specific wavelengths to pass through it.

Cut off Filters

The cut off filters transmit the radiation very near to accuracy.  However, this is only achieved for a specific band of wavelengths by using multiple numbers of absorption filters which filter a single wavelength more than one time.

Interference Filters

Interference filters are dependent upon the concept of wave interference. Some of the radiations are transmitted and other is reflected by these filters.

 An interference filter is composed of a transparent dielectric sandwiched between two semitransparent metallic films. These two glass plates to protect the filter.

The thickness of the dielectric and the reflectivity of the metallic films are selected because as this give more accurate results. These factors control the transmitted wavelengths having very narrow bandwidth.