Development of the hottest X-ray fluorescence spec

2022-07-27
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Development of X-ray fluorescence spectrometry (I) a brief historical review roentgen discovered X-ray in 1895. In 1927, the chemical element HF was discovered by X-ray spectrum, which proved that X-ray spectrum could be used for elemental analysis. After the Second World War, the wavelength dispersive X-ray fluorescence spectrometer was first developed by the US naval laboratory in 1948. In the 1950s, only some western universities and research institutes conducted research on the theory and experiment of this technology. In the west, it was only in the mid-1960s that this technology was promoted in the industrial sector. At that time, China began to introduce the early commercialized X-ray fluorescence spectrometer. Since the 1970s, the Chinese Academy of Sciences, the first machinery department, the Ministry of metallurgy and the Ministry of geology have all organized forces to develop domestic X-ray spectrometers, and established professional organizations such as Dandong ray group. Due to the appearance of semiconductor detectors, the energy dispersive X-ray spectrometer without doubt began to appear in the 1970s. Due to the emergence of microcomputer, X-ray spectrum analysis technology developed rapidly in hardware, software and methods from the late 1970s to the early 1980s. Since the 1990s, there have been some private small enterprises developing and producing X-ray instruments in China. Various research institutes and universities have also conducted in-depth research in various fields of X-ray spectrum analysis, such as fine structure analysis of X-ray absorption end, total reflection X-ray spectrum analysis, development of x-ray focusing elements, PIXE, synchrotron radiation, etc., and have made certain achievements. The state also has various funds such as science and technology innovation fund to support the research and development of new instruments. At the same time, in the western developed countries, with the development of space, biology, medicine, environment and material science, the demand further stimulates the development of X-ray spectroscopy, which is mainly reflected in the development of various new detectors, new excitation sources and related components. The superior ability of new components has led to new testing technology. X-ray spectroscopy is facing a great development. Van grieken[1,2,3] and others have made a detailed introduction in this regard

(II) basic configuration of X-ray spectrometer

x-ray spectrometer is mainly composed of excitation and detection systems in addition to the sample room. Instruments can be roughly divided into wavelength dispersion (WD) and energy dispersion (ED). Wavelength dispersive type is that the dispersive element diffracts the characteristic X-rays of different energies to different angles, and the detector needs to move to the corresponding position to detect the rays of a certain energy. In the energy dispersive type, the dispersive system is removed, and the detected X-rays are resolved by the energy resolution of the detector itself. The wavelength dispersive type has high energy resolution, while the energy dispersive type can measure multiple spectral lines at the same time

(III) related technologies of X-ray fluorescence spectrum analysis

(IV) X-ray tube

the traditional wavelength dispersive X-ray spectrometer needs kW X-ray tube as the excitation source, and it must be water-cooled because of its high power. There are a variety of target materials to choose from, which can be made into end window or side window. The thickness of be window is generally between mm. With the appearance of small wavelength dispersion instruments in recent years, such high-power X-rays are not required because the compact data and curves of the instruments are dynamically displayed and combined with the experimental process, and bent crystal focusing is adopted Before purchase, the X-ray tube used is generally between the tiles, and water cooling is not required. Air cooling is enough

because the energy dispersive instrument removes the dispersive system, the detector is very close to the sample and increases the solid angle of detection, it only needs an X-ray tube with a comprehensive consideration rate of several watts to tens of watts. Because of its low power and less heat dissipation, it only needs natural cooling or air cooling

with the emergence of new electric refrigeration semiconductor detectors and the development of large-scale integrated circuits, the energy dispersive X-ray spectrometer can be made smaller and smaller, thus stimulating the development of small X-ray tubes. These small X-ray tubes have been emerging in recent years, and many new technologies have been adopted, such as using laser instead of hot filament, plating the target on the transmission target behind the beryllium window, etc. Its volume is only the size of peanuts, and its power is only a few watts, or even less than a watt. A Swedish patent [4] claims that the x-ray focusing element can be used to export the rays emitted by the small X-ray tube from the small hole in the middle of the SDD detector to make an X-ray pen that integrates excitation and detection. Several commercially available handheld X-ray spectrometers are available

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