Atomic spectroscopy is the determination of elemental composition by its electromagnetic or mass spectrum. The analysis of the electromagnetic spectrum of components is named Optical Atomic Spectroscopy. Electrons exist in energy levels within an atom. These amounts have well defined energies and electrons moving between them need to absorb or emit energy equal to the difference between them. In optical spectroscopy, the energy consumed to move an electron into a livelier level or the energy emitted as the electron moves to a less active energy level is in the shape of a photon. The wavelength of the emitted radiant energy is directly linked to the electronic transition that has occurred. Since every component has a distinctive electronic structure, the wavelength of light emitted is a special property of every individual element. Since the orbital configuration of a large atom might be complicated, there are lots of electronic transitions which may occur, each transition causing the emission of a characteristic wavelength of light.
Performing atomic absorption spectroscopy requires a main light source, an atom source, a monochromator to isolate the particular wavelength of light to be measured, a sensor to measure the light correctly, electronic equipment to process the information signal and a data screen or reporting system to reveal the results. The light source normally used is a hollow cathode lamp HCL or an electrodeless discharge lamp EDL. Generally speaking, another lamp is used for every component to be determined, although sometimes, a few elements could be combined in a multi-element lamp. Before, photomultiplier tubes are used as the sensor. However, in most modern devices, solid-state sensors are now used. Flow Injection Mercury Systems FIMS are specialized, easy-to-operate atomic absorption spectrometers for the determination of mercury. These tools use a high-performance single-beam optical system using a low-pressure mercury lamp and solar-blind sensor for optimum performance.
The Environmental, food, pharmaceutical, petrochemical, chemical/industrial and geochemical/mining industries use nuclear spectroscopy for fundamental elemental determinations on a diverse variety of samples. There are three widely accepted analytical methods — atomic absorption, atomic emission and mass spectrometry. The Most frequent techniques now are flame atomic absorption spectroscopy, graphite furnace atomic absorption spectroscopy, inductively coupled plasma atomic Absorption spectroscopic-AAS and inductively coupled plasma mass spectrometry icp-ms.