Laser induced breakdown spectroscopy on metallic alloys: Solving inhomogeneous optically thick plasmas

CSigma graphs: A new approach for plasma characterization in laser-induced breakdown spectroscopy

“…By comparing computed line profiles with the experimental ones, the temperature, electron density and densities of emitting species were determined. A similar approach was used by D'Angelo et al [12,13] for a laser-induced plasma generated from a ternary alloy Co-Cr-Mo. In [12], a two-region plasma picture of a hot dense core surrounded by a colder periphery was considered whereas a cylinder-symmetrical plasma column with a parabolic temperature distribution was used in [13].…”

“…A similar approach was used by D'Angelo et al [12,13] for a laser-induced plasma generated from a ternary alloy Co-Cr-Mo. In [12], a two-region plasma picture of a hot dense core surrounded by a colder periphery was considered whereas a cylinder-symmetrical plasma column with a parabolic temperature distribution was used in [13]. A heuristic model for LIBS was developed by Wester and Noll [14], based on the use of the radiation transport equation to calculate the spectrum emitted by the laserinduced plasma, described by a two-shell model surrounded by ambient gas.…”

“…The effect of the first group of parameters is quantified in the k t coefficient, introduced in our previous work [20], which depends on the oscillator strength and other atomic data of the transition as well as on the plasma temperature. The k t concept has been used by other groups to estimate selfabsorption in LIBS experiments [24][25][26][27][28] or as a starting point for the development of self-absorption models [9,12,13]. However, the k t coefficient allows comparing the optical depth of lines of a given element and ionization state if the lines have the same line shape.…”

Semiempirical model for analysis of inhomogeneous optically thick laser-induced plasmas

“…(6), as well as standard statistical distributions. The input parameters are the initial plasma length, the temperature in the plasma core, and the total density of Co, which were estimated in a previous work from the simpler 2-region approach [34]. The model is semiempirical so some information is obtained from the experiment (i.e.…”

“…In a previous work by our group, a simple model of a two-region plasma was implemented to characterize the physical state of a laserinduced plasma produced on a metallic alloy [34]. The plasma parameters that reproduced the experimental profiles were obtained by a fitting procedure carried out by a self-made computer program which took into account self-absorption as well as plasma inhomogeneity, and without employing any reference sample.…”