Study On Qualitative And Quantitative Analytical Method For Elements In Solid State Matter By Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a novel approach of spectral analysis. Analysis of elemental in unknown samples using LIBS has several advantages such as simultaneous multi-element analysis, fast and no radiation, it has giant potential prospect in power generation, geological and mineral, Conservation, Metallurgy, archaeology and so on.This article presents the fundamental and its application of LIBS at first. Then in view of the exists drawbacks including artificial peak picking in qualitative analysis and poorly long-term stability caused by the laser energy fluctuation, We resolving these key problems by principle and technology, developing an apparatus for coal quality analysis, it can measuring the ash value, calorific value and sulfur contents in coal, promoting the practicability of this technology.The main works of this paper are as follows:1. Determine of the electron number density and plasma temperature, the criterion of LTE conditions are reviewed. A program for computing the plasma parameter is developed by Lab VIEW, an algorithm for estimate the width of the spectral line is established based on Guass formula, the electron number density and plasma temperature are estimated based on Boltzmann distribution and Saha formula.2. The second difference and threshold methods are employed to smooth spectral lines and pick peaks, characteristic spectrum of several elements matches the NIST database, and realized automatic spectral line identification and qualitative analysis of the basic composition of sample.3. We built a negative feedback system for stabilize the laser power, measuring the power shift between the output value and presets value of laser energy, and then calculates the controller action by PID control, adjust the voltages of xenon lamp automatically, make sure the energy fluctuation are within±3.2. It has enhancing the practicality and reliability of LIBS.4. The calibration model of proximate analysis are established by a second-order polynomial multivariate inverse regression, improving the calculation precision of spectral line intensity by normalize. Fitting the line intensity of the related element to obtain the ash value and calorific value of the sample, with the accuracy estimated to be4.61%and7.32%.5. An apparatus for coal quality analysis are developed based on above research, it can perform proximate analysis within30-60s, this product has the feature of facilitated in operation, accurate in measurements, steady in long-term performance.