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Title: Compositional, spatial and temporal analysis of laser produced plasmas
Author: Williams, C. L.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1993
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This thesis describes the application of the methods of Laser Induced Breakdown Spectroscopy (LIBS) and Laser Induced Fluorescence (LIF) for the analysis of laser-produced plasmas. Spatial and temporal evolution as well as the compositional structure of expanding plumes were investigated. One of the main aims was to use the aforementioned spectroscopic techniques to improve on the detection limits for elements present in a laser-produced plasma evolving in air at atmospheric pressure. In the first set of experiments the technique of LIBs is explored for the analysis of solid samples. Radiation from a high power pulsed Nd:YAG laser is focused onto the sample to produce a luminous plasma. The fluorescence emitted from the plasma as it cools is analysed using spectroscopic equipment. Two different methods of detection and data acquisition were used, namely a photomultiplier based system and a gated diode array detector arrangement. Several solid standard steel targets were studied. The environments in which the plasma were allowed to form were varied, including vacuum, buffer gases, atmospheric air and flowing buffer gases &43 atmospheric air. As well as obtaining information regarding the population levels and temperatures of the species in the plasmas, the technique was used as an analytical tool for compositional analysis. Calibration curves were constructed for two elements [Cu and Cr] under different ambient conditions and comparisons made between the results. The second set of experiments is devoted to the technique of LIF and its application as an analytical tool in the detection of chromium in steel samples. LIF is an extension of the LIBS method because initially a laser-produced plasma is generated in the same manner as with the LIBS studies; the plasma plume is allowed to expand into an environment of air at atmospheric pressure.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available