Two-color interferometry and shadowgraphy characterization of an orthogonal double-pulse laser ablation

Abstract

Orthogonal double pulse laser ablation on aluminum target at atmospheric pressure was studied by time-resolved optical emission spectroscopy, shadowgraphy and two-color interferometry. Studies were realized as a function of the distance from the first pulse plasma induced in air to the sample surface. The evolution of the electron and neutral particles densities were determined by two-color interferometry. Line intensification mechanisms are discussed based on the interferometry results and the plumes interaction dynamics. It was found that the sample heating by the preablation pulse could contribute to the observed emission enhancement.

Optimal emission enhancement in orthogonal double-pulse laser-induced breakdown spectroscopy

“…Thus, the vaporized material will expand to a larger volume at a faster rate than in normal atmospheric conditions, i.e. SP-LIBS [16,41,42]. As a result, the particle number density is reduced, which is translated in a slower recombination rate.…”

“…In a previous work [41], we observed that the temperature near the sample surface in the pre-ablative configuration exceeds the Al target fusion value for up to 40 μs. Then, thermal energy is transferred to the sample facilitating the ablation process due to a reduction of the deposited energy required to vaporize the sample.…”

“…The air spark also heats the sample surface inducing changes in its optical properties [41,43,44]. In a previous work [41], we observed that the temperature near the sample surface in the pre-ablative configuration exceeds the Al target fusion value for up to 40 μs.…”

“…Therefore, this SE can be attributed to environmental changes near the target produced by the first spark. This plasma induced in the air just above the sample surface reduces the background gas density [16,40,41]. Thus, the vaporized material will expand to a larger volume at a faster rate than in normal atmospheric conditions, i.e.…”

Chemical etching method assisted double-pulse LIBS for the analysis of silicon crystals

“…The analytical performance of the DP-LIBS technique is strongly dependent on the selection of the experimental conditions. Several research groups focused on optimizing the experimental parameters by DP laser systems [22][23][24] to improve the sensitivity of LIBS. The enhancement in emission line intensity using collinear DP excitation is due to an increase in ablation efficiency, longer plasma life time and higher plasma temperature.…”