CDS&E: Orientational High and Low Field Ion Mobility Calculator with Gas Accommodation

在化学部门化学测量和成像项目的支持下，印第安纳大学-普渡大学的Carlos Larriba-Andaluz教授正在努力提高我们对离子迁移率光谱（IMS）原理的基本理解，这是一种通过气相中几何和电子结构的差异分离带电分子的技术。这项技术被广泛应用于机场安全、健康研究和环境科学等领域。Larriba-Andaluz小组试图通过弥合经典假设与以前被忽视的次要效应之间的差距来改善这一重要分析工具的性能，这些次要效应现在已知对现代仪器的性能有重大影响。通过传播用户友好的IMS软件，加强了研究的影响。一个辅助目标是通过向机械工程专业的学生和K-12学生拓展对化学的理解。外联工作特别寻求妇女和少数民族的参与，鼓励他们参与科学和工程。IMS正在成为现代质谱（MS）的一个组成部分。这导致了IMS仪器的重要进步，提高了分辨率、传输和灵敏度。尽管有这些进步，但在理解基础理论方面并没有相应的进步。这个问题是具有挑战性的，因为IMS是根据尺寸而不是电荷来分离分析物的，而尺寸是气体参数、施加的力以及离子和缓冲气体之间潜在相互作用的复杂组合。随着IMS仪器的分辨率达到数百，现有的简化理论往往会被证明是不够的。通过放宽Chapman和Cowling的第一个碰撞积分理论，Larriba-Andaluz教授和他的团队正在1)评估高场密度比、永久偶极矩和首选取向的影响；2)通过量子力学（QM）和分子动力学（MD）与动力学理论的耦合来解决撞击-再发射碰撞理论的弹性/扩散非弹性性质；3)评估气相离子结构压实导致的碰撞截面（CCS）变化。目的是：1)通过放松动量传递方程的线性化，改进现有的自由分子体系的理论知识；2)研究碰撞时的动量交换，从而提高对分子水平上能量交换如何发生的理解；3)缩小现有的新型IMS系统与对分离如何发生的理论认识之间的差距。所开发的算法的自由传播应该刺激新计算的发展，导致更好的优化和仪器的发展，以及在复杂样品成像中的新应用的出现。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging program in the Chemistry Division, Professor Carlos Larriba-Andaluz at Indiana University-Purdue University in Indianapolis is working to improve our fundamental understanding of the principles of Ion Mobility Spectrometry (IMS), a technique that separates charged molecules through differences in their geometrical and electronic structure in the gas phase. This technique is utilized in a wide range of applications, such as airport security, health research, and environmental sciences. The Larriba-Andaluz group seeks to improve the performance of this important analysis tool by bridging the gap between classical assumptions and the influence of previously neglected secondary effects that are now known to have consequential impact on the performance of modern instruments. The impact of the research is enhanced through dissemination of user-friendly IMS software. An ancillary goal is expanding understanding of chemistry by outreach both to mechanical engineering students and to K-12 students. The outreach efforts especially seek to engage women and minorities, encouraging their participation in science and engineering.IMS is becoming an integral part of modern mass spectrometry (MS). This has resulted in important advances in IMS instrumentation with improved resolution, transmission, and sensitivity. Despite these advances, there has not been a parallel improvement in understanding the underlying theory. The problem is challenging, because IMS separates analytes based on size over charge, where the size is an intricate combination of gas parameters, forces applied and potential interactions between ion and buffer gas. As IMS instruments reach resolving powers of several hundreds, the existing simplified theory will often prove inadequate. By means of relaxing Chapman and Cowling's first collision integral theory, Professor Larriba-Andaluz and his team are 1) evaluating the effect of high field to density ratios, permanent dipole moments, and preferred orientations; 2) addressing the elastic/diffuse inelastic nature of the impingement-reemission collision theory through the coupling of quantum mechanics (QM) and molecular dynamics(MD) to kinetic theory; and 3) assessing collision cross section (CCS) modification due to ion structure compaction in the gas phase. The aims are to 1) improve existing theoretical knowledge in the free molecular regime through relaxation of linearization of the momentum transfer equations; 2) study momentum exchange upon impingement, thereby improving understanding of how energy exchange occurs at the molecular level; and 3) close the existing gap between novel existing IMS systems and the theoretical understanding of how separation occurs in them. Free dissemination of the algorithms developed should spur development of new calculations, leading to better optimization and development of instrumentation, and the emergence of new applications in imaging for complex samples.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.