PNNL

Abstract

The analysis of hydrogen (H) and its isotopes is crucial to several applications, including nuclear forensics and safeguards, characterization of nuclear fission and fusion reactor materials, geochemistry, and space exploration. Laser-induced breakdown spectroscopy (LIBS) is a promising tool for the real-time analysis of H and its isotopes. However, the accurate, quantitative analysis via optical emission spectroscopy is challenging due to H contamination on sample surfaces, residual H in the analysis environment, and spectral line broadening. Here, we use ultrafast laser ablation coupled with spatially and temporally resolved optical emission spectroscopy to characterize plasmas produced from Zircaloy-4 targets with varying H isotopic compositions in a He gas environment. The impact of varying ambient gas pressure, the spatial distribution, and temporal histories of species viz., H I, D I, and Zr I on Zircaloy-4 plasma spectral features are reported. H and Zr emission features have different pressure dependencies and are separated in both space and time in laser-produced plasmas. Results highlight the importance of employing temporally and spatially resolved analyses for studying H isotopes using laser ablation coupled with optical emission spectroscopy.