Evaluation of a Novel Femtosecond Laser Ablation System for In Situ Analysis Based on Two-Dimensional Galvanometer Scanners

Uneven energy distribution of femtosecond lasers presents a significant challenge for single-spot analysis, which often leads to concave ablation craters. This study assesses the performance of a femtosecond laser ablation system for in situ analysis using novel galvanometer scanners. A galvanometer rapidly moved the laser beam focus to create craters with a small beam spot. We first examined the inductively coupled plasma mass spectrometry (ICP-MS) signal sensitivity to laser parameters, establishing a strong linear correlation with the laser energy, repetition rate, scanning ablation area, and galvanometer scanning frequency. Elemental fractionation analysis of NIST SRM 610 suggests minimal bias, with fractionation indices of different elements approaching unity. Subsequently, the elemental concentration of six reference material glasses was measured by fsLA-ICP-MS to evaluate the elemental quantification capabilities of the Galvo-femtosecond laser (Galvo-fsLA). The laser's capability for in situ U-Pb dating was demonstrated by concordant U-Pb ages of five zircon reference materials that are highly consistent with the ID-TIMS ages reported previously. Finally, the reliability of the new Galvo-fsLA for isotope analysis was verified by the accurate determination of radiogenic Hf, Pb isotopes, and stable Cu isotopes, all agreeing well with their reference values within uncertainties. These assessments underscore the significant potential of Galvo-fsLA for enhanced accuracy and precision of single-spot in situ analysis.