Mass spectrometry of atmospheric pressure plasmas
Mass spectrometry of atmospheric pressure plasmas
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DOI：
10.1088/0963-0252/24/4/044008
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发表时间：
2015-08-01
影响因子：
3.8
通讯作者：
Benedikt, J.
中科院分区：
文献类型：
--
作者：
Grosse-Kreul, S.;Huebner, S.;Benedikt, J.
大气压非平衡等离子体（APPs）是自由基、可燃物以及各种离子和光子的有效来源，范围可达真空紫外光谱区。对这些物质的详细研究对于了解和调整工业或医疗应用中APP与固体或液体材料相互作用期间的预期效果非常重要。在这方面的贡献，质谱检测中性和离子的应用程序，基本的物理现象有关的采样过程及其对中性和离子通量的测量密度的影响，将讨论的机遇和挑战。结果表明，稳定的中性和自由基的测量需要一个适当的实验设计，以减少束背景比，有小的光束失真膨胀到真空中，并仔细设置在电离器中的电子能量，以避免自由基的形成，通过离解电离。所测量的离子组成敏感地取决于进料气体中存在的杂质的程度以及用于从膨胀的中性离子混合物中提取离子的离子光学器件的设置。离子能量的测定被提出作为一种方法，以表明所分析的离子是来自大气压等离子体。
Atmospheric pressure non-equilibrium plasmas (APPs) are effective source of radicals, metastables and a variety of ions and photons, ranging into the vacuum UV spectral region. A detailed study of these species is important to understand and tune desired effects during the interaction of APPs with solid or liquid materials in industrial or medical applications. In this contribution, the opportunities and challenges of mass spectrometry for detection of neutrals and ions from APPs, fundamental physical phenomena related to the sampling process and their impact on the measured densities of neutrals and fluxes of ions, will be discussed. It is shown that the measurement of stable neutrals and radicals requires a proper experimental design to reduce the beam-to-background ratio, to have little beam distortion during expansion into vacuum and to carefully set the electron energy in the ionizer to avoid radical formation through dissociative ionization. The measured ion composition depends sensitively on the degree of impurities present in the feed gas as well as on the setting of the ion optics used for extraction of ions from the expanding neutral-ion mixture. The determination of the ion energy is presented as a method to show that the analyzed ions are originating from the atmospheric pressure plasma.