What Is a Hollow Cathode Lamp?
Hollow cathode lamp (Hollow cathode lamp), in order to solve the practical measurement problem of atomic absorption method, proposed by A. Walsh in 1955, it is a special form of low-voltage glow discharge sharp line light source, because hollow cathode lamp emits sharp line light source , Meet the conditions of atomic absorption spectrometry.
- light source
- The function of the light source is to emit the characteristic resonance line absorbed by the ground-state atoms of the measured element, so it is called a nartow-line source.
- The basic requirements for the light source are: the half-width of the wavelength of the emitted radiation is significantly smaller than the half-width of the absorption line, the radiation intensity is large enough, the stability is good, the background signal is low (less than 1% of the resonance radiation intensity), and the service life is long. Hollow cathode lamp with the measured element as the cathode. [1]
- Hollow cathode lamp (HCL) is the most commonly used sharp line light source. It is a low-pressure gas discharge tube, which mainly has an anode (tungsten rod) and a hollow cylindrical cathode (consisting of a metal or alloy compound of the measured element). The cathode and anode are sealed in a glass tube with an optical window and filled with a low-pressure (a few hundred Pa) inert gas (neon or argon). [1]
- Hollow cathode lamp (HCL) is a special form of low voltage
- Be careful not to reverse the polarity.
- To make the lamp
- Multi-element hollow cathode lamp: A variety of metal powders are mixed and pressed and sintered according to a certain ratio, and a multi-element hollow cathode lamp can be produced as a cathode. Up to seven elements, such as Al-Ca-Cu-Fe-Mg-Si-Zn. As long as the wavelength is changed, several elements can be measured simultaneously on one lamp. The disadvantage is that the radiation intensity, sensitivity and life are not as good as single element lamps. The more combinations, the worse the spectral characteristics and the larger the spectral line interference. [1]
- Under normal working conditions, hollow cathode lamps are a practical sharp line light source. The spectrum emitted by hollow cathode lamps is mainly the spectrum of cathode elements. Therefore, hollow cathode lamps with various measured elements can be made by using different measured elements as cathode materials. The disadvantage is that it is inconvenient to measure one element for another lamp. [1]