Abstract The hydrogen isotopes in liquid and frozen water samples were analyzed by laser ablation molecular isotopic spectrometry (LAMIS), which employs the molecular emission from laser-induced plasma for isotope analysis. Molecular emission bands of OH and NH radicals were observed, and their spectral features were characterized in accordance with sample matrix and measurement conditions. The OH and NH bands exhibit different emission behavior, which was attributed to formation kinetics and thermodynamic factors. Under optimized condition, isotopic shift between hydrogenated (OH and NH) and deuterated (OD and ND) species was measured at individual rotational branches. By using these molecular bands, the partial least squares regression (PLSR) structure was established for quantitative analysis of hydrogen isotope and evaluated by cross-validation in terms of accuracy and precision. The PLSR result was good with root mean square error of prediction (RMSEP) of 0.3–0.7% for all species. Particularly, the case using OH/OD emission from liquid water revealed the most accurate result with RMSEP of 0.33%. It was affected by the quality and reproducibility of spectral data determined by utilized species. This study not only supports the behavioral understanding of molecular radicals in laser-induced plasma, but also identifies the feasibility of LAMIS for real-time application to quantitative analysis in various sample matrices.

中文翻译：

---

使用激光诱导等离子体对液态和冷冻水的分子发射进行氢同位素分析

摘要 采用激光烧蚀分子同位素光谱法 (LAMIS) 分析液体和冷冻水样中的氢同位素，该光谱法利用激光诱导等离子体的分子发射进行同位素分析。观察了OH和NH自由基的分子发射带，并根据样品基质和测量条件表征了它们的光谱特征。OH 和 NH 波段表现出不同的发射行为，这归因于形成动力学和热力学因素。在优化条件下，在单个旋转分支处测量氢化（OH 和 NH）和氘化（OD 和 ND）物种之间的同位素位移。通过使用这些分子带，建立了偏最小二乘回归（PLSR）结构用于氢同位素的定量分析，并通过交叉验证在准确度和精密度方面进行评估。PLSR 结果很好，所有物种的预测均方根误差 (RMSEP) 为 0.3-0.7%。特别是，使用来自液态水的 OH/OD 排放的情况显示出最准确的结果，RMSEP 为 0.33%。它受到所用物种确定的光谱数据的质量和可重复性的影响。这项研究不仅支持对激光诱导等离子体中分子自由基的行为理解，而且还确定了 LAMIS 实时应用于各种样品基质定量分析的可行性。所有物种为 7%。特别是，使用来自液态水的 OH/OD 排放的情况显示出最准确的结果，RMSEP 为 0.33%。它受到所用物种确定的光谱数据的质量和可重复性的影响。这项研究不仅支持对激光诱导等离子体中分子自由基的行为理解，而且还确定了 LAMIS 实时应用于各种样品基质定量分析的可行性。所有物种为 7%。特别是，使用来自液态水的 OH/OD 排放的情况显示出最准确的结果，RMSEP 为 0.33%。它受到所用物种确定的光谱数据的质量和可重复性的影响。这项研究不仅支持对激光诱导等离子体中分子自由基的行为理解，而且还确定了 LAMIS 实时应用于各种样品基质定量分析的可行性。