The excitation light source is a main component of the atomic fluorescence spectrometer. Under certain conditions, the fluorescence intensity is proportional to the emission intensity of the excitation light source. At present, the most widely used excitation light source in atomic fluorescence spectrometers is the hollow cathode lamp. In order to ensure that the hollow cathode lamp can not only emit sufficient luminous intensity but also maintain a certain service life, a short-pulse and high-current power supply mode is usually adopted. Which instrument is the hollow cathode lamp used in? The hollow cathode lamp is a widely used laboratory instrument, usually used to measure gas discharge phenomena in fields such as electronics, physics, and chemistry. It is widely applied in the field of analytical chemistry, mainly in atomic absorption spectroscopy (AAS) and fluorescence spectroscopy (FLS). When the elements in the hollow cathode lamp escape from the cathode in a vapor state, they are excited to produce extremely narrow characteristic spectral lines. By embedding different metal materials on cathodes made of different materials, different hollow cathode lamps can be manufactured. A potassium element lamp can be used to measure sodium because it contains sodium elements; a zinc element lamp can be used to measure copper because it contains copper elements. Moreover, using a sodium lamp to measure potassium, a calcium lamp to measure magnesium, a magnesium lamp to measure calcium, a copper lamp to measure zinc, an iron lamp to measure manganese, a manganese lamp to measure iron, a lead lamp to measure cadmium, and a cadmium lamp to measure lead can all successfully find peaks, indicating that these lamps contain the elements to be measured. However, during the ignition test of these lamps, there is no significant change in absorbance, which indicates that the content of the elements to be measured in these lamps is extremely low. A potassium lamp can successfully determine sodium because the content of sodium elements in the potassium lamp is equivalent to that of potassium elements, and the intensity of the characteristic spectral lines generated by the excitation of sodium elements escaping from the cathode lamp in a vapor state can meet the analytical needs. The working principle of the hollow cathode lamp The hollow cathode lamp (HCL) is powered by an adjustable pulse width constant current source, and its principle is shown in Figure 1. The frequency of the hollow cathode lamp power supply pulse modulation signal is 200 Hz (i.e., the signal period T = 5 ms), and the pulse width (t) and duty cycle (D = t:T) are controlled by a computer. The value of t can be flexibly set from 3.2 μs to 2496 μs. During the experiment, the instrument adopts a dual-channel measurement mode in which two hollow cathode lamps are alternately powered and a single photomultiplier tube detects the atomic fluorescence signal. The power supply pulse width of the hollow cathode lamp is selected as 167 μs (D = 1:30), 250 μs (D = 1:20), 500 μs (D = 1:10), or 1000 μs (D = 1:5). The service life of the hollow cathode lamp The service life of the hollow cathode lamp is more than 1000 hours under a lamp current of 5 mA. If it is not used for a long time, it should be powered on and lit for 1-2 hours every 2-3 months. Revival of the lamp: The reverse connection degassing method is adopted. Reverse-connect the two poles of the lamp to the positive and negative poles of the power supply, and light it for 20-30 minutes under the maximum working current to make the cathode red-hot, so as to achieve the purpose of degassing. Before using the hollow cathode lamp, if it is preheated at 1/3 of the working current for 0.5-1.0 hours and regularly activated, its working life can reach thousands of hours. When replacing the hollow cathode lamp, be careful not to leave fingerprints on the lamp window. Most of the element lamps used in atomic absorption spectrometers are hollow cathode lamps, which are consumable parts. Therefore, attention should be paid to the maintenance of hollow cathode lamps at ordinary times. The above is an introduction to "the service life and working principle of the hollow cathode lamp", hoping to be helpful to everyone. Source: Wang Pang 1576, Computing Techniques for Geophysical and Geochemical Exploration