Applicability of resonant two-photon ionization in supersonic beam mass spectrometry to halogenated aromatic hydrocarbons
Applicability of resonant two-photon ionization in supersonic beam mass spectrometry to halogenated aromatic hydrocarbons
复制标题
共振双光子电离在超声束质谱中对卤代芳烃的适用性
DOI：
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发表时间：
1985
期刊：
影响因子：
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通讯作者：
D. Lubman
中科院分区：
文献类型：
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作者：
R. Tembreull;C. H. Sin;Ping Li;H. Pang;D. Lubman
本文研究了在超声束质谱仪中使用共振双光子电离作为电离源时可能出现的问题。这里研究的特定类型的分子包括单取代和双取代卤代苯以及卤代甲苯、苯酚和苯胺衍生物。在一个简单的单色R2PI方案中，许多邻位取代化合物被发现没有有效地电离。这似乎是由于相邻取代基之间的空间和库仑相互作用的组合，可能提高了分子相对于未取代情况的电离势，也降低了吸附的Frank-Condon跃迁几率，从而使电离变得困难。这些效应定性地与取代基团的总电子释放和抽出性质有关，因此可以合理地预测哪些取代苯将服从这一技术。在取代基间相互作用很小的对位取代化合物中，电离通常被发现是有效的。然而，也有一些情况，如碘取代苯，由于超快的无辐射过程，没有明显的电离发生。参考文献57篇，附图5幅，表5张。
In this work, problems are studied that may arise in the use of resonant two-photon ionization as an ionization source in supersonic beam mass spectrometry. The particular classes of molecules studied herein include mono- and disubstituted halogenated benzenes and halogenated toluene, pheno, and aniline derivatives. In a simple one-color R2PI scheme many of the ortho-substituted compounds are found not to ionize efficiently. This appears to be due to a combination of steric and coulombic interactions between adjacent substituent groups that may raise the ionization potential of the molecule relative to the unsubstituted case and also decrease the Franck-Condon transition probability for absorption thus making ionization difficult. These effects have been qualitatively related to the overall electron releasing and withdrawing properties of the substituent groups so that reasonable predictions can be made regarding which substituted benzenes will be amenable to this technique. In para-substituted compounds in which there is little interaction between substituent groups, ionization is generally found to occur efficiently. However, there are cases such as the iodo-substituted benzenes where ionization does not occur apparently due to ultrafast radiationless processes. 57 references, 5 figures, 5 tables.