Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), P.O. Box 6980, 76049 Karlsruhe, Germany.
Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), P.O. Box 3640, 76021 Karlsruhe, Germany.
Phys Chem Chem Phys. 2019 Sep 21;21(35):18877-18892. doi: 10.1039/c9cp03326b. Epub 2019 Aug 22.
We present high-resolution trapped ion mobility spectrometry (TIMS) measurements for fullerene ions in molecular nitrogen. Three different charge states were studied (monocations, monoanions and dianions) with fullerenes ranging in size from C to C. Ions were prepared by either electrospray ionization (ESI, for mono- and dianions) or by atmospheric pressure chemical ionization (APCI, for monocations) of a preformed fullerene soot extract solution. We demonstrate that TIMS allows to identify (and separate) constituent isomers in favorable cases. Using DFT calculations based on known condensed phase structures and trajectory method (TM) calculations we can reproduce the experimental CCS for fullerenes up to C to within 0.5%. Using candidate structures based on quantum chemical predictions, we have also obtained structural information for fullerenes C-C- a size range not previously accessed in condensed phase studies. We find that soluble fullerenes in this size have near-spherical rather than tubular structures. While the TM programs presently available for CCS modelling do a remarkably good job at describing the ion mobility of high (and even giant) fullerenes we observe a slight but systematic size-dependent deviation between CCS values and our best computational fits which may reflect systematic bonding changes as the cage size increases.
我们呈现了富勒烯离子在氮气中的高分辨率囚禁离子淌度谱（TIMS）测量结果。研究了三种不同的电荷态（单电荷、单负电荷和双负电荷），富勒烯的尺寸范围从 C 到 C。离子通过预形成的富勒烯烟尘提取物溶液的电喷雾电离（ESI，用于单电荷和双负电荷）或大气压化学电离（APCI，用于单电荷）来制备。我们证明 TIMS 允许在有利的情况下识别（和分离）组成异构体。使用基于已知凝聚相结构和轨迹方法（TM）计算的 DFT 计算，我们可以在 0.5%以内重现实验 CCS 至 C 范围内的富勒烯。使用基于量子化学预测的候选结构，我们还获得了 C-C-的结构信息，这是以前在凝聚相研究中无法获得的尺寸范围。我们发现，在这个尺寸范围内的可溶性富勒烯具有近球形而不是管状结构。虽然目前用于 CCS 建模的 TM 程序在描述高（甚至巨型）富勒烯的离子迁移率方面表现出色，但我们观察到 CCS 值与我们最佳计算拟合之间存在微小但系统的尺寸依赖性偏差，这可能反映了随着笼尺寸的增加，键合的系统性变化。
