Fundamental investigations of ion mobility and separation of isomers by high resolution ion mobility spectrometry

拟议研究项目的主要目标是开发一种紧凑的高分辨率离子迁移率光谱仪(IMS)，其分辨率为R&GT；300，探测极限为ppt级，快速响应时间不到一秒，同时不同的非放射性离子源可以根据应用轻松地与IMS耦合。主要的技术挑战是设计一种如此紧凑的IMS，以满足上述所有分析要求，以及开发运行该系统所需的复杂电子设备。这包括开发1 GV/A、150 kHz的低噪声、高增益放大器，以及根据达到的分辨率轻松调整带宽的可能性，用于操作离子快门的快速高压开关，以及用于漂移环电极的直接低功率供电的紧凑高压级联电路。为了优化IMS的设计，需要进行详细的实验表征。此外，还将开发考虑对分析性能的所有相关影响的分析和数值模型，并进行实验验证。具体地说，将数值模拟IMS内从电离区到探测器板的离子传输。然而，为了进行可行的模拟，必须仔细考虑主要由离子快门和移动的离子云引起的暂态电场不均匀、金属表面的离子放电效应、离子和中性物质的扩散和对流输运现象以及不同离子源的电离特性。此外，在离子通过快门注入时，将测量不同离子源在电离区内产生的离子密度和离子分布，并将其用作数值模拟的可行初始条件。本研究项目集中在用于离子产生的非放射性电子发射体、弱X射线源和光电离源。经过连续的优化循环，描述分析性能的所有相关影响的经过实验验证的理论模型和具有可交换离子源的紧凑型高分辨率IMS将在项目结束时可用。一个可能的项目扩展将集中于面向应用的系统优化，重点是呼气分析和生物过程监测。此外，一个纳米电喷雾电离源将耦合到IMS上，用于快速分析液体。

The main objective of the proposed research project is the development of a compact high-resolution ion mobility spectrometer (IMS) with a resolving power of R > 300, detection limits down to ppt-levels and fast response times of less than a second while different non-radioactive ion sources can be easily coupled to the IMS depending on the application. The main technical challenges are designing such a compact IMS that meets all the analytical requirements mentioned above and the development of complex electronics required for operating the system. This includes the development of a low-noise, high-gain amplifier with 1 GV/A at 150 kHz and the possibility to easily adjust the bandwidth with respect to the achieved resolving power, fast high-voltage switches for operating the ion shutter and a compact high-voltage cascade circuit for a direct low-power supply of the drift ring electrodes. In order to optimize the IMS design a detailed experimental characterization is needed. Furthermore, analytical and numerical models considering all relevant effects on the analytical performance will be developed and experimentally validated. In particular, the ion transport inside the IMS from the ionization region to the detector plate will be numerically simulated. However, for feasible simulations the transient electrical field inhomogeneities mainly caused by the ion shutter and moving ion clouds, ion discharge effects at metallic surfaces, diffusion and convective transport phenomena of ions and neutrals as well as the ionization properties of different ion sources have to be carefully considered. In addition, the ion density and ion distribution generated inside the ionization region by different ion sources will be measured at the moment of ion injection through the shutter and used as feasible initial conditions for the numerical simulations. This research project concentrates on a non-radioactive electron emitter, a weak x-ray source and a photoionization source for ion generation. After successive optimization cycles both an experimentally validated theoretical model describing all relevant effects on the analytical performance and a compact high-resolution IMS with exchangeable ion sources will be available at the end of the project. A possible project extension would concentrate on application-oriented system optimization with a focus on breath analysis and bioprocess monitoring. Furthermore, a nano-electrospray ionization source will be coupled to the IMS for fast analysis of liquids.