425 research outputs found
Atomic Emission, Absorption and Fluorescence in the Laser-induced Plasma
The main result of our efforts is the development and successful application of the theoretical model of laser induced plasma (LIP) that allows a back-calculation of the composition of the plasma (and the condensed phase) based on the observable plasma spectrum. The model has an immediate experimental input in the form of LIP spectra and a few other experimentally determined parameters. The model is also sufficiently simple and, therefore, practical. It is conveniently interfaced in a graphical user-friendly form for using by students and any laboratory personnel with only minimal training. In our view, the model opens up the possibility for absolute analysis, i.e. the analysis which requires no standards and tedious calibration. The other parts of this proposal (including plasma diagnostics) were somewhat subordinate to this main goal. Plasma diagnostics provided the model with the necessary experimental input and led to better understanding of plasma processes. Another fruitful direction we pursued was the use of the correlation analysis for material identification and plasma diagnostics. Through a number of computer simulations we achieved a clear understanding of how, where and why this approach works being applied to emission spectra from a laser plasma. This understanding will certainly improve the quality of forensic and industrial analyses where fast and reliable material identification and sorting are required
Spectrum standardization for laser-induced breakdown spectroscopy measurements
This paper presents a spectra normalization method for laser-induced
breakdown spectroscopy (LIBS) measurements by converting the recorded
characteristic line intensity at varying conditions to the intensity under a
standard condition with standard plasma temperature, degree of ionization, and
total number density of the interested species to reduce the measurement
uncertainty. The characteristic line intensities of the interested species are
first converted to the intensity at a fixed temperature and standard degree of
ionization but varying total number density for each laser pulse analysis.
Under this state, if the influence of the variation of plasma morphology is
neglected, the sum of multiple spectral line intensities for the measured
element can be regarded proportional to the total number density of the
specific element, and the fluctuation of the total number density, or the
variation of ablation mass, was compensated for by the application of this
relationship. In the experiments with 29 brass alloy samples, the application
of this method to determine Cu concentration shows a significant improvement
over generally applied normalization method for measurement precision and
accuracy. The average RSD value, average value of the error bar, R2, RMSEP, and
average value of the maximum relative error were: 5.29%, 0.68%, 0.98, 2.72%,
16.97%, respectively, while the above parameter values for normalization with
the whole spectrum area were: 8.61%, 1.37%, 0.95, 3.28%, 29.19%, respectively.Comment: LIBS; Normalization; quantitative measurement; plasma propert
Recommended from our members
Final Report: Development of Laser Excited Atomic Fluorescence and Ionization Methods, May 1, 1988 - December 31, 1998
Recommended from our members
Development of laser excited atomic fluorescence and ionization methods
Progress report: May 1, 1988 to December 31, 1991. The research supported by DE-FG05-88ER13881 during the past (nearly) 3 years can be divided into the following four categories: (1) theoretical considerations of the ultimate detection powers of laser fluorescence and laser ionization methods; (2) experimental evaluation of laser excited atomic fluorescence; (3) fundamental studies of atomic and molecular parameters in flames and plasmas; (4) other studies
Sample Preparation Techniques In Analytical Chemistry
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