![]() A low pressure of argon in the lamp insures that the line width from the hollow cathode lamp is less than the line width of the absorbing species. Collisions of excited state sputtered atoms with argon atoms will lead to broadening of the output of the hollow cathode lamp and potentially lead to the same problem described above with the use of a continuum source. A schematic diagram of an electrodeless discharge lamp is shown in Figure 2. Schematic diagrams of two spiral tungsten filaments mounted in graphite tube support the aliquot sample. The pressure of the argon is low to minimize collisions of argon atoms with sputtered atoms. Hollow cathode lamps (HCLs) are available for most of the elements. With this understanding we can ask why the hollow cathode lamp has a low pressure of argon filler gas. Therefore, hollow cathode lamps, which emit intense narrow lines of radiation specific to the element being analyzed, are needed for atomic absorption measurements. from publication: Characterization of hollow cathode and parallel plate microplasmas: Scaling and. Reducing the slit width on a continuum source to a level that would provide a narrow enough line to respond to atomic absorption would reduce the power so that it would not be much above the noise. Download scientific diagram Cross-sectional schematic of the hollow cathode plasma source. The problem with reducing the slit width is that it reduces the number of photons or source power reaching the sample. What is the problem with reducing the slit width of the monochromator to get a narrower line? Hollow cathodes operate in a self-heating mode, in which the external heater is turned off during operation and the cathode insert is heated by plasma bombardment. Download scientific diagram Schematic diagrams of the distribution of sample positions in the mesh hollow cathode discharge deposition system. Atomic absorption line superimposed onto the overall output of a continuum source/monochromator system. Electrodeless Discharge Lamp (Schematic Diagram) Our earlier article Types of light sources in Atomic Absorption Spectroscopy covered the essential features of the two commonly used light sources hollow cathode camps and electrode less discharge lamps. Hollow cathode schematic showing the cathode tube, insert, and heater enclosed in a keeper electrode. ![]()
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