No abstract

No abstract

Moderate cylindrical cavity was used to regularize the laser-induced plasma for signal strength enhancement and precision improvement in laser-induced breakdown spectroscopy (LIBS). A polytetrafluoroethylene (PTFE) plate of 1.5 mm thickness with diameter of 3 mm was fabricated. It was placed closely on a sample surface and a laser pulse was shot through the center of the hole to the sample. Using coal as samples, it was verified that the configuration both enhanced the spectral line intensity and reduced shot-to-shot fluctuation, showing its great potential in improving the precision of LIBS analysis.

No abstract

Aluminum alloys were analyzed for minor components and trace impurities using double pulse resonance-enhanced laser-induced plasma spectroscopy. The first laser pulse at 532 nm ablated the sample. The second laser pulse at 396.15 nm resonantly excited the Al atoms to rekindle the plasma plume. Emissions from Mg, Cu, Si, and Na were observed. At laser energies below the damage threshold, the analyte emissions were already orders of magnitude above the background noise. Nonresonant probes of comparable sensitivity would melt and deform the sample surface. Because of the lower etch rate of resonant probes, depth profiling at nanometer resolution was possible. Using this method, the variation of [Na] with depth was measured for high-purity samples. In contrast, nonresonant probes required 5 times the fluence and proportionally poorer resolution. Worse yet, the associated heating and laser remelting modified the [Na] profile.