Materials analysis using laser-based spectroscopic techniques

Abstract

In this paper several laser-based spectroscopic methods capable of detecting low concentrations of a particular element are described, with particular emphasis on the contrasting techniques of Laser-Induced Breakdown Spectroscopy (LIBS), and Resonance Ionisation Mass Spectroscopy (RIMS). Simple mathematical treatments, based on thermodynamic considerations and rate equation models, are given for both systems, allowing semiquantitative analysis from the magnitudes of observed signals. Experimental results are presented for both methods. For LIBS these include the determination of the concentration of alloy constituents, the detection of surface contaminants and the use of measured line intensities to calculate electron temperatures in laserproduced plasmas. For RIMS, detection of the geologically important element rhenium (Re) was accomplished in the gas phase at a level of 4 x 10 8 atoms/cm 3 , and the relative proportions of the stable isotopes 185 Re and 187 Re were measured with the use of a quadrupole mass filter. In addition, an optogalvanic system is described, which was used to calibrate the wavelength of the RIMS resonance to an accuracy of 0.013 nm.

Comparative study of different methodologies for quantitative rock analysis by Laser-Induced Breakdown Spectroscopy in a simulated Martian atmosphere

“…In the Chaléard et al [20] and Goddard/Loge approaches [24,25] which use calibration curves, s refers to the element and C s is the elemental concentration. In this case, Eq.…”

“…Assuming validity of the Chaléard et al [20] and Goddard/Loge [24,25] approaches, Eq. (5) gives the intensity ratio for two elements A and B contained in the same sample:…”

“…The analytical approach commonly used for the correction of matrix effects (referring to the Goddard/Loge approach [24,25]) is based on normalization of the emission signal to a reference signal, generally an emission line of the major element of the marix. In a previous work performed in our laboratory, Chaléard et al [20] proposed to normalize the LIBS signal to an experimental temperature coefficient and to the acoustic signal emitted by the shock wave produced by the plasma expansion and supposedly proportional to the vaporized mass.…”

Application of Laser-Induced Breakdown Spectroscopy to Real-Time Elemental Monitoring of Iron and Steel Making Processes

“…A calibration of the LIBS signal is necessary for quantitative analysis. Despite the fact that the LIBS processes involved are complex, the emission intensity from the atomized species can be described by the following equation with the assumption of uniform plasma temperature 34) I n K g E kT…”

Industrial applications of temperature and species concentration monitoring using laser diagnostics

“…The material contained in the plasma is atomized, and light is released corresponding to a unique wavelength for each element. Despite the fact that the processes involved are complex, the emission intensity from the atomized species, with the assumption of a uniform plasma temperature, can be described by the following equation [94]:…”