Method for Measuring Element Concentration Based on Spectroscopic Laser-Induced Breakdown Spectroscopy

Abstract

The invention discloses a method for measuring elemental concentration through laser-induced breakdown spectroscopy based on spectrophotometry, which belongs to the technical field of atomic emission spectrum measurement. The method is characterized in that a laser light is divided into two beams by an optical spectroscope; and then, the two laser light beams are reflected by a reflector, so that the included angle between the incident direction of the two laser light beams and the normal direction of the surface of a sample is 0-90 degrees. Plasmas generated by laser impaction are mainly expanded toward a direction perpendicular to the surface of the sample, therefore, the shielding effect of the plasmas on the laterally incident laser is weak, so that more laser energy can reach the surface of the sample, and the ablation quality can be improved; and by combining a technology of forming aerosols above the surface of the sample to optimize the experimental conditions for plasma generation, the method ensures that the plasmas can be generated more easily and the electronic density is higher. The method disclosed by the invention increases the repeatability of measurement, thereby facilitating the improvement of the goodness of fit and forecast accuracy of a calibration model.

Description

Technical field [0001] The invention relates to a method for measuring element concentration by laser induced breakdown spectroscopy based on spectroscopy, and belongs to the technical field of atomic emission spectrometry. Background technique [0002] Laser-induced breakdown spectroscopy (LIBS), also known as laser-induced plasma spectroscopy, is a new material element analysis technology developed in the late 20th century. The working principle of laser-induced breakdown spectroscopy technology is: under the action of a strong laser pulse, the material on the sample surface is excited into plasma and decays rapidly. During the decay process, photons of a specific frequency are radiated to produce characteristic spectral lines, their frequency and intensity The information contains the element type and concentration information of the analysis object. Laser-induced breakdown spectroscopy technology has the advantages of low operating cost, fast measurement speed, high sensitiv...

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Problems solved by technology

[0003] However, because the laser action point of laser-induced breakdown spectroscopy technology 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, plasma temperature, electron The difference in physical parameters such as density leads to low repeatability of laser-induced breakdown spectroscopy 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 use of laser-induced breakdown spectroscopy The measurement accuracy of the technology directly measuring the sample cannot be guaranteed, which limits the application of laser-induced breakdown spectroscopy technology in actual production

[0004] Simple pretreatment of the sample, such as pressing the sample powder, can increase the repeatability of the laser-induced breakdown spectroscopy measurement, and grinding and mixing the sample uniformly can reduce the influence of the matrix effect, but this still cannot completely eliminate the inaccurate measurement. The degree of certainty and various interferences, direct measurement can not achieve the accuracy required for industrial production, the pretreatment method of the sample needs further research

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