Structural information from ion mobility measurements: Effects of the long-range potential
Structural information from ion mobility measurements: Effects of the long-range potential
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DOI：
10.1021/jp961623v
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发表时间：
1996-10-03
影响因子：
--
通讯作者：
Jarrold, MF
中科院分区：
文献类型：
--
作者：
Mesleh, MF;Hunter, JM;Jarrold, MF
在最近的一些研究中，有关大的多原子离子的结构的信息已经推导出气相离子迁移率测量通过比较在氦气中测量的迁移率估计为假设的几何形状，使用硬球投影近似。为了研究这种方法的有效性，我们比较了迁移率计算使用硬球投影近似的范围内的富勒烯（C-20-C-240）的轨迹计算与更现实的He-富勒烯的潜力。我们所采用的He-富勒烯势是两体6-12相互作用的总和加上离子诱导偶极相互作用的总和，使用在80-380 K温度范围内测量的C-60（+）在氦中的迁移率进行校准。对于所研究的系统，离子和缓冲气体之间的长程相互作用有一个小的，小于10%，在室温下计算的迁移率的影响。然而，影响并不是微不足道的，在许多情况下，如果要从测量的离子迁移率进行正确的结构分配，则有必要考虑长程相互作用。
In a number of recent studies, information about the structure of large polyatomic ions has been deduced from gas phase ion mobility measurements by comparing mobilities measured in helium to those estimated for assumed geometries using a hard sphere projection approximation. To examine the validity of this approach, we have compared mobilities calculated using the hard sphere projection approximation for a range of fullerenes (C-20-C-240) to those determined from trajectory calculations with a more realistic He-fullerene potential. The He-fullerene potential we have employed, a sum of two-body 6-12 interactions plus a sum of ion-induced dipole interactions, was calibrated using the measured mobility of C-60(+) in helium over an 80-380 K temperature range. For the systems studied, the long-range interactions between the ion and buffer gas have a small, less than 10%, effect on the calculated mobility at room temperature. However, the effects are not insignificant, and in many cases it will be necessary to consider the long-range interactions if the correct structural assignments are to be made from measured ion mobilities.