Īn HCL can also be used to tune light sources to a specific atomic transition by making use of the optogalvanic effect, which is a result of direct or indirect photoionization. These photons will then excite the atoms in the sample, which will release their own photons and be used to generate data. As these excited atoms decay to lower states, they will emit photons. Both the buffer gas and the sputtered cathode atoms will in turn be excited by collisions with other atoms/particles in the plasma. The buffer gas ions will then be accelerated into the cathode, sputtering off atoms from the cathode. A large voltage across the anode and cathode will cause the buffer gas to ionize, creating a plasma. Īn HCL usually consists of a glass tube containing a cathode, an anode, and a buffer gas (usually a noble gas). An HCL takes advantage of the hollow cathode effect, which causes conduction at a lower voltage and with more current than a cold cathode lamp that does not have a hollow cathode. for atomic absorption spectrometers) and as a frequency tuner for light sources such as lasers. JSTOR ( December 2015) ( Learn how and when to remove this template message)īasic diagram of a hollow-cathode lamp Hollow-cathode lamps from an atomic absorption spectrometerĪ hollow-cathode lamp (HCL) is type of cold cathode lamp used in physics and chemistry as a spectral line source (e.g.Unsourced material may be challenged and removed.įind sources: "Hollow-cathode lamp" – news Please help improve this article by adding citations to reliable sources. Also, by establishing a reference system from standards of known concentration, unknown samples can be analyzed quantitatively.This article needs additional citations for verification. Because element concentration is a function of its wavelength intensity, the concentration of the target element can be determined. Following dispersion of these wavelengths (including the characteristic wavelength of the analyte), the AAS instrument detector measures wavelength intensity. Atomizer and monochromator instruments are key to making the AAS device work.Īfterwards, the analyte is excited by different light sources and emits a mixture of wavelengths. This reduced intensity is characteristic of a given element and helps to identify it, as well as to determine its concentration.ĪAS takes advantage of different radiation wavelengths that are absorbed by different atoms. When absorption occurs, the result is a light spectrum that has reduced light intensity in one or more of its areas. This light source has been set to defined wavelengths, and the metal atoms in the sample absorb these wavelengths (or not). The sample is then exposed to a source of radiation, which typically originates from a light source. In graphite furnace AAS, the liquid sample is introduced into the cuvette directly, where it is transformed into a fine mist. Afterwards, this mist is fed into a flame to break up any remaining molecular bonds. In the case of flame AAS, this involves atomizing the sample, which involves the creation of a fine mist dispersion. Sample preparation and introduction involve rendering a liquid or solid sample into a state that the instrument can process for elemental analysis.
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