| In laser-induced breakdown spectroscopy (LIBS), a laser pulse of sufficiently high power is focused to produce an irradiance that exceeds the material's breakdown threshold of 10-100 MW cm{dollar}sp{lcub}-2{rcub}{dollar}. If the electric field in the focused laser beam is greater than the dielectric field strength of the material it encounters somewhere in the focal volume, breakdown occurs at that point and eventually results in the formation of a transient, highly energetic plasma. For analytical purposes, the emitted electromagnetic radiation is spectrally resolved, and the emitting species in the laser-induced plasma are identified and quantified by their unique spectral wavelengths and their line intensities.; Fundamental investigations of laser-induced plasmas have resulted in a better understanding of their spatial and temporal development. When exploring the lead level populations in a LIBS plasma, it was determined that over the first 15 {dollar}mu{dollar}s of the plasma's life time the energy distribution of the excited atoms does not follow a Boltzmann distribution.; Two different types of LIBS instrumentation have been constructed and evaluated. A benchtop instrument for laboratory use, and a battery-powered, portable instrument for field use. Both were evaluated for elemental determinations in alloy, soil, paint, ore and organic matrices.; Investigations were conducted concerning the variables that influence the precision of LIBS measurements. These included the choice of analytical line, sample movement, number of measurements, laser stability, detector settings, surface morphology, and data treatment.; The effect of a change in matrix on LIBS measurements was explored. Five different sensitivities were observed for the analysis of zinc and chromium in aluminum, copper, graphite, sand, and potassium bromide matrices. One possible method for compensation was through the use of an internal standard. The internal standard can be selected based on the standard criteria, with the addition of the evaluation of the temporal development of the analysis and internal standard elements signals.; We also report on the investigation of the usefulness of LIBS as a process monitor in a mining facility. Satisfactory results have been obtained for both phosphate rock and iron ore minerals in the laboratory. Current research efforts have focused on the transferring of the LIBS technology from the laboratory to the processing site. |
