Measurements with Laser Ablation Molecular Isotopic Spectrometry (LAMIS) are usually performed in atmosphere for rapid isotope analysis, and an understanding of molecule formation via plasma–air chemical reactions is important for quantitative analysis by LAMIS. In this work, the expansion of a plasma plume from ablation of pure aluminum in air is studied with time- and space-resolved monochromatic imaging and emission spectroscopy. The distributions of neutral Al and O atoms and AlO radicals formed through plasma chemical reactions are characterized. The emission spectra of the AlO bands of a B²Σ⁺–X²Σ⁺ system are recorded and the rotational–vibrational temperature was obtained through fitting experimental spectra. Inter-molecular vibrational band interference is well re-constructed, and self-absorption of bandheads, especially for the (0–0) band, is corrected. Interpretation of the spatial–temporal evolutions of plasma species and plasma temperature provides insights into the formation mechanism of AlO radicals in laser-induced plasma.

中文翻译：

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激光诱导等离子体中不均匀羽流与空气相互作用引起的分子形成

激光烧蚀分子同位素光谱法（LAMIS）的测量通常在大气中进行，以便进行快速同位素分析，了解通过等离子体-空气化学反应形成分子对于LAMIS定量分析非常重要。在这项工作中，利用时间和空间分辨单色成像和发射光谱研究了空气中纯铝烧蚀引起的等离子体羽流的膨胀。表征了通过等离子体化学反应形成的中性Al和O原子以及AlO自由基的分布。一个B的频带的AlO的发射光谱² Σ ⁺ -X ² Σ ⁺记录系统，并通过拟合实验光谱获得旋转振动温度。分子间振动带干扰得到了很好的重建，并且带头的自吸收得到了纠正，尤其是对于（0-0）带。对等离子体种类和等离子体温度的时空演化的解释提供了对激光诱导的等离子体中AlO自由基形成机理的见解。