A critical review of the two-temperature theory and the derivation of matrix elements. High field ion mobility and energy calculation for all-atom structures in light gases using a 12-6-4 potential
A critical review of the two-temperature theory and the derivation of matrix elements. High field ion mobility and energy calculation for all-atom structures in light gases using a 12-6-4 potential
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对双温度理论和矩阵元素推导的批判性回顾。
DOI：
10.1016/j.talo.2023.100191
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Larriba-Andaluz, Carlos
中科院分区：
文献类型：
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作者：
Gandhi, Viraj D.;Hua, Leyan;Chen, Xuemeng;Latif, Mohsen;Larriba-Andaluz, Carlos
离子迁移率已经成为分析化学许多方面的普遍工具，因为它能够在将化合物送入质谱仪之前分离气相中的化合物。为了理解这种复杂的分离是如何发生的，有必要彻底解释离子-气体相互作用。特别是，这份手稿的目的是用双温度近似描述高场碰撞背后的物理原理。双温理论最近被成功地用来描述多原子离子的迁移率，因此有必要进行适当的解释。文中给出了一个简明的描述，以及它成功预测离子漂移速度背后的严格的数学论证。此外，还提供了获得高阶迁移率近似的方程(包括矩阵元素)的详细过程，使这项工作适合于离子迁移率的初学者和专家。特别讨论了基温的选择及其与离子的有效温度和漂移速度的关系。比较了12-6-4势和麦克斯韦模型，指出了用麦克斯韦模型计算低场和高场时可能存在的误差。使用我们的内部算法IMOS，与以前的逐次逼近和实验结果进行了对比，测试了直到第四次的逐次逼近，显示了渐近收敛，以及对单原子气体和小离子的良好一致性。
Ion mobility has become a ubiquitous tool in many aspects of Analytical Chemistry due to its ability to separate compounds in the gas phase prior to feeding them to a Mass Spectrometer. To understand how this complex separation occurs, it is necessary to thoroughly explain the ion-gas interaction. In particular, this manuscript aims to describe the physics behind the collisions at high fields using the two-temperature approximation. The two-temperature theory has been recently employed to describe the mobility of polyatomic ions quite successfully and thus a proper account is warranted. A concise description is provided along with rigorous mathematical arguments behind its success at predicting the ion's drift velocity. Moreover, a thorough procedure for obtaining the equations (including the matrix elements) for higher-order mobility approximations is also provided with high detail, making this work suitable for beginners and experts in ion mobility. In particular, a discussion is brought forth on the choice of the base temperature and its relation to both the effective temperature and the drift velocity of the ion. A comparison between a 12-6-4 potential and the Maxwell model is made, pointing at the possible errors of using the Maxwell model for low- and high-field calculations. Using our in-house algorithm IMoS, successive approximations up to the fourth are tested against previous ones and against experimental results, showing both, asymptotic convergence, as well as a good agreement for monoatomic gases and small ions.