Method for improving element measurement precision by using plasma space restricting effect
A plasma and space-limited technology, applied in the field of atomic emission spectrometry, which can solve the problems of LIBS interference, inability to achieve accuracy, and limit the application of LIBS, to enhance spectral line intensity and signal-to-noise ratio, increase electron density and temperature, improve The effect of goodness of fit
Active Publication Date: 2011-09-14
TSINGHUA UNIV
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[0003] However, because the laser action point of LIBS is very small, the amount of ablated material is very small, and the matrix effect is very obvious for inhomogeneous and anisotropic materials; at the same time, the fluctuation of laser energy, the fluctuation of physical parameters such as plasma temperature and electron density Differences lead to low repeatability of LIBS measurement; in addition, the influence of environmental parameters and the electronic noise of the internal components of the instrument are likely to interfere with LIBS; therefore, the measurement accuracy of direct measurement samples using LIBS cannot be guaranteed, which limits the use of LIBS in Application in production
[0004] Simple pretreatment of the sample, for example, the repeatability of LIBS measurement can be increased by pressing the sample powder, and the influence of the matrix effect can be reduced by grinding and mixing the sample evenly, but this still cannot completely eliminate the measurement uncertainty and various Interference, direct measurement can not achieve the accuracy required for industrial production, the pretreatment method of the sample needs further research
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Embodiment 1
[0034] Taking the measurement of C element in coal by LIBS as an example, the method of improving the measurement accuracy of elements by using the plasma space confinement is described.
[0035]1) at first use the known ten kinds of standard coal samples of each element mass concentration to analyze, and the mass concentration and volatile matter content of the main elements of each coal sample are as shown in table 1; Utilize four kinds of pits described in the technical scheme of the present invention The method of making the hole or the cavity is used to process the samples separately.
[0036] Table 1. Composition of standard coal samples
[0037]
[0038] 2) Use the laser-induced plasma spectroscopy system to detect the coal sample: the pulsed laser 1 is used as the excitation light source, and the laser light emitted from the laser is focused by the focusing lens 2 and then acts on the pit or cavity formed on the surface of the coal sample or close to the surface At...
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The invention discloses a method for improving element measurement precision by using plasma space restricting effect, and belongs to the technical field of atomic emission spectroscopy measurement. The method improves the measurement precision of a laser induced plasma spectrum technology by forming a pot hole or a cavity on the surface of a sample to be measured or the upper part tightly attached to the surface. The plasma generated by striking the laser at the bottom of the pot hole or the cavity has higher electron density and higher signal-to-noise ratio due to the space restricting effect compared with the plasma directly generated on a plane, and is favorable for improving the detection limit of trace elements in the sample to be measured. The measurement method has the characteristics of strong repeatability, good calibration optimization and high forecasting precision.
Description
technical field [0001] The invention relates to a method for improving the measurement accuracy of elements by utilizing space limitation, and belongs to the technical field of atomic emission spectrum measurement. Specifically, the measurement method involved in this method is laser-induced plasma spectroscopy (LIBS for short). Potholes or cavities, and then improve the measurement conditions, to achieve the purpose of improving the accuracy of element measurement. Background technique [0002] LIBS is a brand-new material element analysis technique developed in the late 20th century. The working principle of LIBS is: under the action of strong laser pulses, the material on the surface of the sample is excited to become plasma and decays rapidly. During the decay process, photons of specific frequency are radiated and characteristic spectral lines are generated. The frequency and intensity information of the sample contains the analysis object. The element type and concen...
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Login to View More IPC IPC(8): G01N21/63G01N1/28
Inventor 李政王哲袁廷璧
Owner TSINGHUA UNIV