Ablation laser femtoseconde à haute cadence de tir et basse energie couplée à une détection ICPMS: Résultats préliminaires
Résumé
Recent advances in the field of ultra short pulse laser (femtosecond) allow now to integrate such sources in compact structures dedicated to laser ablation/ICPMS. We present a new infrared femtosecond laser device operating at low energy ( <100 μJ) and high repetition rate ( <10 kHz) providing a new analytical approach for laser ablation. Our results show that signal stability is improved when using the femtosecond laser. Combining the high repetition rate and the low energy features of this laser, a flash ablation approach was developed and was found to drastically enhance the signal to background ratio of the LA/ICPMS. This flash ablation consists in removing a large amount of material in a very short period of time and in transferring the resulting thin particles to the ICPMS. The process was found to be reproducible and quantitative. Detection limits obtained on glass samples could then be improved by a factor within 10 to 40 compared to a 266 nm nanosecond laser ablation. Conversely, the low energy femtosecond ablation can be adjusted to ablate very small amount of material. Depth profile analysis on Cr/Ni multilayer revealed a depth profile resolution better than 20 nm per pulse.