Atomic Emission and Optical Emission Spectrometers

Atomic emission and optical emission spectrometers determine analyte concentration via a quantitative measurement of the optical emission from excited atoms.  Analyte atoms in solution are aspirated into the excitation region where they are desolvated, vaporized, and atomized by a flame, discharge, or plasma. These high-temperature atomization sources provide sufficient energy to promote the atoms into high energy levels. The atoms decay back to lower levels by emitting light. Since the transitions are between distinct atomic energy levels, the emission lines in the spectra are narrow. The spectra of samples containing many elements can be very congested, and spectral separation of nearby atomic transitions requires a high-resolution spectrometer. Since all atoms in a sample are excited simultaneously, they can be detected simultaneously using a polychromator with multiple detectors. This ability to simultaneously measure multiple elements is a major advantage of AES compared to atomic-absorption (AA) spectroscopy.

Atomic emission and optical emission spectrometers characterize all forms of emission from atoms. These are principally electrons, x-rays and optical photons. So strictly, therefore, AES should include the spectral measurement of all types of atomic emissions.

Optical emission describes emissions in the optical range, i.e. UV-Vis-IR. Such emissions are characteristically different from emissions at very short wavelengths (x-rays and gamma rays), and from emissions at long wavelengths (far-IR and radio waves). In particular, different types of instruments are used to detect them. Optical emissions are generally detected with optical spectrometers.

Thus OES is a part of AES, and all of the techniques of interest could be called AES, but since they all exclusively measure optical emissions with optical spectrometers, the use of OES is much more precise.

• Direct-Current Plasma (DCP)
  Direct-current plasma (DCP) is an excitation source for atomic emission and optical emission spectrometers. DCP is created by an electrical discharge between two electrodes. A plasma support gas is...
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