Results of a transient simulation of a drift tube ion mobility spectrometer considering charge repulsion, ion loss at metallic surfaces and ion generation
Results of a transient simulation of a drift tube ion mobility spectrometer considering charge repulsion, ion loss at metallic surfaces and ion generation
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DOI：
10.1007/s12127-012-0095-z
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发表时间：
2012-12-01
影响因子：
--
通讯作者：
Zimmermann, Stefan
中科院分区：
文献类型：
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作者：
Langejuergen, Jens;Cochems, Philipp;Zimmermann, Stefan
通过优化几何结构和操作参数，IMS的选择性和灵敏度都可以显著提高。然而，找到这些参数和几何形状需要在任何操作时间准确了解IMS内的电场和离子浓度。此外，还必须考虑金属表面的离子损失和移动离子云引起的空间电荷效应。当使用非放射性电子发射体时尤其如此，非放射性电子发射体由于其较小的电离体积而在类似于放射性β源的电子电流下产生非常高的空间电荷密度。这可能导致主要由库仑排斥引起的IMS分辨率降低。在这项工作中，提出了一个瞬态模型，该模型可以详细了解IMS内的电场，同时考虑离子扩散和迁移以及离子损失和库仑排斥。这种有限元模型提供了良好的协议之间的模拟IMS光谱和实验数据，特别是当考虑空间电荷效应和库仑排斥。该模型被用来设计一个短漂移管IMS与显着提高分辨率。此外，该模型允许考虑离子-离子和离子-中性反应，例如离子生成、电荷转移反应和离子-离子复合。此外，流体动力学可以被认为是建模抽吸型IMS所需的。
With optimized geometry and operating parameters both IMS selectivity and sensitivity can be significantly increased. However, finding these parameters and geometry requires an accurate knowledge of the electrical field and the ion concentration within the IMS at any time of operation. Furthermore, the ion loss at metallic surfaces and space charge effects caused by the moving ion cloud must be considered. This is particularly true when using non-radioactive electron emitters which generate a comparably high space charge density at electron currents similar to radioactive beta-sources due to their smaller ionization volume. This can lead to a reduced IMS resolution mainly caused by coulomb repulsion. In this work a transient model which enables a detailed view on the electric field within the IMS considering ion diffusion and migration as well as ion loss and coulomb repulsion is presented. This finite element model provides excellent agreement between simulated IMS spectra and experimental data especially when considering space charge effects and coulomb repulsion respectively. The model is used to design a short drift tube IMS with significantly improved resolution. Furthermore, this model allows considering ion-ion and ion-neutral reactions, such as ion generation, charge transfer reactions and ion-ion recombination. Moreover, fluid dynamics can be considered as required for modeling aspiration type IMS.