Ion Mobility Mass Spectrometry of Au25(SCH2CH2Ph)18 Nanoclusters
Ion Mobility Mass Spectrometry of Au25(SCH2CH2Ph)18 Nanoclusters
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DOI：
10.1021/nn1012447
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发表时间：
2010-08-01
期刊：
影响因子：
17.1
通讯作者：
Dass, Amala
中科院分区：
文献类型：
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作者：
Angel, Laurence A.;Majors, Lance T.;Dass, Amala
离子迁移质谱（IM-MS）可以根据离子的大小、形状和电荷以及质荷比来分离离子。本文报道了Au-25（SCH 2CH 2 Ph）（18）（-）纳米团簇的实验IM-MS和IM-MS/MS数据。Au-25（SCH 2CH 2 Ph）（18）（-）的IM-MS显示出窄的对称漂移时间分布，表明仅存在一种结构。IM-MS/MS很容易区分由六个[SR Au SR Au SR]“斯台普斯”（其中R = CH 2CH 2 Ph）和Au-13核制成的外保护层的碎片。斯台普斯的碎裂特征在于Au-4（SR）（4）从簇中的主要损失和八个不同条带的形成。连续的八个谱带包含越来越多的AuISmRn-产物离子，这是由于外层Au 21 X14-（其中X = S或SCH 2CH 2 Ph）的递增碎裂。在每个单独的频带中的物种的流动性表明，较低的质量物种表现出更大的碰撞截面，有利于识别的AuISmRn-产品。在谱带下方，在1200-2800 m/z区域中，可以观察到与Au-13核的碎裂有关的产物离子。在低质量50-1200 m/z区域中，还观察到碎片离子如Au（SR）（2）（-）、Au-2（SR）（3）（-）、Au-3（SR）（4）（-）和Au-4（SR）（s）（-）（，对应于大碎片Au 25-x（SR）（18-（x+1））。研究表明，主要的大碎片类型为Au ~（21）X ~（14-/+）和Au ~（17）X ~（10-/+），负、正模式下的电子数分别为8和6。这表明在选择Au-25（SR）（18）结构时，几何因素可能超过电子因素。
Ion mobility mass spectrometry (IM-MS) can separate ions based on their size, shape, and charge as well as mass-to-charge ratios. Here, we report experimental IM-MS and IM-MS/MS data of the Au-25(SCH2CH2Ph)(18)(-) nanocluster. The IM-MS of Au-25(SCH2CH2Ph)(18)(-) exhibits a narrow, symmetric drift time distribution that indicates the presence of only one structure. The IM-MS/MS readily distinguishes between the fragmentation of the outer protecting layer, made from six [SR Au SR Au SR] "staples' where R = CH2CH2Ph, and the Au-13 core. The fragmentation of the staples is characterized by the predominant loss of Au-4(SR)(4) from the cluster and the formation of eight distinct bands. The consecutive eight bands contain an increasing variety of AuISmRn- product ions due to the incremental fragmentation of the outer layer of Au21X14-, where X = S or SCH2CH2Ph. The mobility of species in each individual band shows that the lower mass species exhibit greater collision cross sections, facilitating the identification of the AuISmRn- products. Below the bands, in the region 1200-2800 m/z, product ions relating to the fragmentation of the Au-13 core can be observed. In the low mass 50-1200 m/z region, fragment ions such as Au(SR)(2)(-), Au-2(SR)(3)(-), Au-3(SR)(4)(-), and Au-4(SR)(s)(-)(are also observed, corresponding to the large fragments Au25-x(SR)(18-(x+1)). The study shows that most of the dominant large fragments are of the general type Au21X14 -/+, and Au17X10 -/+ with electron counts of 8 and 6 in negative and positive mode, respectively. This suggests that geometric factors may outweigh electronic factors in the selection of Au-25(SR)(18) structure.