Zhian Bao

Laser wavelength largely governs analytical accuracy in laser ablation microanalysis. Most routine laser ablation systems rely on 193 nm excimer lasers, while the considerably shorter 157 nm wavelength has only been applied sparingly to in situ microanalysis. This study presents a 157 nm F2 laser system with an optical path purged and protected by an inert gas (N2) and provides a comprehensive performance evaluation of its integration with LA-(MC-) ICP-MS. The 157 nm laser effectively ablates transparent minerals such as quartz and fluorite, producing flat-bottomed craters free of fracturing. Systematic evaluations of trace elements, zircon U–Pb dating, and in situ Hf–B isotopic analyses consistently demonstrate robust analytical performance of the 157 nm laser across diverse in situ microanalysis applications. These capabilities position the 157 nm laser to enhance spatial resolution in highly transparent minerals, facilitating the acquisition of finer-scale chemical insights for a broad range of Earth science and environmental investigations.

Tin (Sn) isotopes in cassiterite (Cas) are important tracers of fluid evolution and Sn sources, but high-precision μm-scale in situ Sn isotope analysis remains constrained by the limited availability of suitable reference materials (RMs). Here, we report the development of a synthetic Cas-matrix RM to serve as a bracketing standard for laser ablation coupled with multicollector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) analysis. Ultrafine cassiterite powder was compressed, sealed in silver tubes, and sintered at 600 °C and 1.0 GPa, producing homogeneous pellets with yields up to 7 g per batch. Two independent laboratories, Northwest University (Xi’an, China) and Leibniz University Hannover (Germany), evaluated the isotopic uniformity (δ124/120Sn) of the pellets using femtosecond laser ablation (fs-LA)-MC-ICP-MS, yielding consistent δ124/120Sn values within analytical uncertainty. Solution nebulization (SN)-MC-ICP-MS analysis of the starting powder and pellet subsamples yielded a recommended δ124/120SnNIST SRM 3161a value of 0.63‰, with an expanded uncertainty (URM) of ∼ 0.07‰ (k = 2) and a precision of ±0.02‰ (2SD, n = 14). The agreement between in situ and solution measurements of natural cassiterite further validates the RM. A total of 28 g of synthetic cassiterite RM was prepared in four batches for distribution to the global geochemical community. This RM will advance Sn isotope analysis in cassiterite by providing a reliable standard for precise in situ measurements and interlaboratory comparison.

A new fused quartz glass reference material, NWU-Qtz, has been developed for in situ Si isotope measurement by femtosecond laser ablation multi-collector inductively coupled plasma-mass spectrometry (fsLA-MC-ICP-MS).

This study investigated matrix effects during in situ Sn isotope analysis using a femtosecond (fs) laser ablation system coupled to a multi-collector ICP-MS.

A natural calcite MNP is presented as potential reference material for microbeam oxygen and carbon isotope analysis.

Microanalysis of silver isotopes in gold (Au) by laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) has been an important tool to reveal the source and enrichment processes of Au.

Two new reference materials, NWU-GN and PY-FHP, have been developed and characterised for the calibration of in situ Pb analyses of sulfide minerals by LA-MC-ICP-MS.

This study compared boron (B) isotopic compositions of six chemically diverse tourmalines (including schorl, dravite, and elbaite types) using 257 nm femtosecond (fs) and 193 nm nanosecond (ns) laser ablation coupled with multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS). Significant matrix effects were observed when non-matrix-matched standards were used, leading to δ¹¹B deviations of −0.70‰ to −0.41‰ for fs-LA and −0.63‰ to −0.57‰ for ns-LA when using dravite GIGT as a bracketing standard for schorl (TOUR1 and TOUR4) and elbaite (TOUR6). In contrast, using GIGT as the matrix-matched bracketing standard in the B analysis of dravites (TOUR2, TOUR3, and TOUR5) yielded significantly lower deviations of −0.22‰ to −0.18‰ for fs-LA and −0.44‰ to 0.12‰ for ns-LA. These findings necessitate matrix-matched standards for precise and accurate in situ measurements of B isotopes. We characterized four natural tourmaline reference materials (TOUR1, TOUR4, TOUR5, and TOUR6) for in situ B isotope analysis using LA-MC-ICP-MS and confirmed their isotopic homogeneity. The measured mean δ¹¹B values were −11.14 ± 0.40‰ (2SD, n = 597), −13.42 ± 0.57‰ (2SD, n = 509), −9.09 ± 0.60‰ (2SD, n = 486), and −8.57 ± 0.17‰ (2SD, n = 164), respectively, agreeing well with those obtained by solution nebulizer (SN)-MC-ICP-MS. Thus, schorl (TOUR1 and TOUR4), dravite (TOUR5), and elbaite (TOUR6) are recommended as candidate matrix-matched tourmaline reference materials for in situ B isotope determination.