[Study on measurement of trace heavy metal Ni in water by laser induced breakdown spectroscopy technique].

The spectroscopy emission characteristics and the detection limit of trace heavy metal nickel in water was studied based on laser induced breakdown spectroscopy technique, with a 1,064 nm wavelength Nd : YAG laser as excitation source, and the echelle spectrometer and ICCD detector were used for spectral separation and high sensitive detection with high resolution and wide spectral range. A round flat solid state graphite as matrix was used for element enrichment for reducing water splashing, extending the plasma lifetime and improving the detection sensitivity, and the experimental sample was prepared by titrating a fixed volume of nickel nitrate solution of different concentrations on a fixed area of the graphite matrix. The results show that the better detection delay time is about 700 ns, the spectrum intensity raises with the concentration increase, a good linear relationship is presented at low concentration with a correlation coefficient 0.

[Study on the automatic recognition method of elemental spectra in laser induced breakdown spetroscopy].

According to the spectral line broadening mechanism of laser induced breakdown spectroscopy, the emission lines from the standard spectral database of NIST were simulated, and they were compared with the spectral data of experiment. In the process of comparison similarity measure was used to measure the similarity between the simulative spectra and the experimental spectra. The automatic recognition method of elemental spectra was studied, and the spectral data of soil between 340 and 345 nm was recognized by computing the proportional coefficients of the spectral lines.

[Study on the automatic extraction method of spectral data features in laser induced breakdown spectroscopy].

According to that the spectral line broadening of laser induced breakdown spectroscopy (LIBS) was lorentz nonlinear function model, using Levenberg-Marquardt (L-M) agorithm to optimally estimate the undetermined parameter in the function, the continuum background radiation and peak position and peak intensity were corrected, and the method of data points automatic extraction for fitting was analysed. Automatic fitting and feature parameter extraction for spectral data of LIBS based on L-M algorithm that was hybrid programming with matrixVB and VB were accomplished,and the result was compared with the origin 7.5 data analysis software which was manual and commonly used and verified its stability and reliability.