Mobilities of carbon cluster ions: Critical importance of the molecular attractive potential
Mobilities of carbon cluster ions: Critical importance of the molecular attractive potential
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DOI：
10.1063/1.475625
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发表时间：
1998-02-08
影响因子：
4.4
通讯作者：
Jarrold, MF
中科院分区：
文献类型：
--
作者：
Shvartsburg, AA;Schatz, GC;Jarrold, MF
迁移率在氦气中的异构体属于漂移管研究中确定的碳簇的主要结构家族（链，单环和双环，石墨片，富勒烯和它们的二聚体）已评估采用一个现实的离子-He相互作用势的轨迹计算。对于所有考虑的物种，在室温下的测量和计算的迁移率之间的协议，提高了至少3倍以上，得到了广泛使用的硬球投影近似。此外，对于3。在78-360 K范围内，轨道计算结果与迁移率测量值符合得很好。这表明C-He成对势仅弱依赖于碳团簇的结构和化学键。因此，这项研究表明，轨迹计算的准确预测的气相迁移率与各种形状和大小的多原子离子的普遍适用性，和这种方法的均匀优于以前使用的近似。特别是，对大富勒烯（n = 120-140）的轨道计算表明，这些笼具有理论上发现的近球形形状，而投影近似将错误地将它们指定为“巴基管”。“它还表明，迁移率可能会受到碳在簇中特定原子上的定位程度的影响，特别是在低温下。(C)1998年美国物理学会。
Mobilities in helium gas for isomers belonging to the major structural families of carbon clusters identified in drift tube studies (chains, monocyclic and bicyclic rings, graphite sheets, and fullerenes and their dimers) have been evaluated by trajectory calculations employing a realistic ion-He interaction potential. For all the species considered, the agreement between the measured and calculated mobilities at room temperature improves by at least a factor of 3 over that obtained with the widely used hard-sphere projection approximation. Furthermore, for 3. large representative sample of clusters belonging to all the above families, the results of trajectory calculations as a function of temperature over the range of 78-360 K are in a good agreement with the measured mobilities. This shows that the C-He pairwise potential is only weakly dependent on the structure and chemical bonding of a carbon cluster. Thus this study demonstrates the universal suitability of trajectory calculations for the accurate prediction of the gas phase mobilities for polyatomic ions with various shapes and sizes, and the uniform superiority of this method over the previously used approximations. In particular, the trajectory calculations for large (n = 120-140) fullerenes show that these cages have near-spherical shapes found by theory, while the projection approximation would erroneously assign them as "buckytubes." It also appears that the mobility may be substantially affected by the degree of char localization on a specific atom in the cluster, especially at low temperatures. (C) 1998 American Institute of Physics.