Atomic Absorption Spectroscopy

Typically, modern chemists make use of Atomic Absorption Spectroscopy to determine, quantitatively, the concentration of small and often trace elements found within certain substances and/or the environment. such measurements can be made due to the sensitive nature of AAS, as measurements that are taken can be into the parts per million (ppm). In principle, AAS works, by using ground state atoms. (which are atoms that have the lowest possible shell orbit to the nucleus due to containing very little energy).

(see bibliography: Smith, R. (2010). ‘Conquering Chemistry: HSC Course’. P.224)

As this diagram shows, these ground state atoms, may absorb the electromagnetic radiation, or bands of visible light as energy given by certain wavelengths

This light then travels past the flame created by an atomizer. Where the atomizer essentially vaporizes an aqueous solution containing the metal ion(s), converting the input ionic solution from into atoms (IE: Na+Na). These atoms, are then shot with a specific ‘matching’ monochromatic light from the selected cathode lamp, whereby some the specific light is absorbed while passing by, This means that not all light will make it through the flame(IE less is detected then what is shot initially). After passing through the flame, the light is then filtered through a monochromator or prism, which works to select a specific wavelength of light, filtering all other unnecessary / unwanted wavelengths out. After this light is sufficiently filtered, the remaining ‘wanted’ wavelength of light is projected into a photomultiplier, which is an instrument that can collect, amplify and then finally measure the amount of light that was detected. The detected light is then displayed and compared directly to the calibration curve (on the output device). From this comparison, scientist can relate the light reading detected from the unknown and can then determine the concentration of the solution as absorbance is always proportionately equal to concentration of the metal atoms within the solution. (meaning that the absorbance will always increase relative to higher