Multiphoton mass spectrometry of clusters: dissociation kinetics of the benzene cluster ions
Multiphoton mass spectrometry of clusters: dissociation kinetics of the benzene cluster ions
复制标题
簇的多光子质谱分析：苯簇离子的解离动力学
DOI：
10.1021/j100324a020
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
E. W. Schlag
中科院分区：
文献类型：
--
作者：
A. Kiermeier;B. Ernstberger;H. Neusser;E. W. Schlag
在超音速射流膨胀中产生了n ≤ 40的中性苯团簇（C6 H6）n，并在反射飞行时间质谱仪中用可调谐紫外激光进行双光子吸收电离。选择光子能量，使得簇离子以少量能量（几百毫电子伏）产生，并且观察到微秒时间尺度上的缓慢衰减。反射质谱仪是直接观察阈值附近团簇所有主要解离路径的仪器。前体离子质量和子离子质量可以通过动能分析明确地分配。特别是苯原子团簇离子的裂解途径高达= 7显示在充分的细节。结果发现，接近解离阈值，eliminationof一个中性苯单体是有利的过程，导致一个电离的集群的大小为n- 1。测量了苯二聚体离子亚稳衰变效率与双光子能量的关系。从得到的分解图中，得到了苯二聚体结合能的第一个纯实验值和苯二聚体阳离子结合能的值。
Neutral benzene clusters (C6H6)„with n up to 40 are produced in a supersonic jet expansion and ionized by two-photon absorption with tunable UV laser light in a reflectron time-of-flight mass spectrometer. Photon energy is chosen so that cluster ions are produced with a small amount of energy (several hundred millielectronvolts) and a slow decay on the microsecond time scale is observed. The reflectron mass spectrometer serves as an instrument for the direct observation of all major dissociation paths of clusters near threshold. The precursor ion mass and the daughter ion mass can be assigned unambiguously by the analysis of kinetic energy. In particular the fragmentation pathways of benzene cluster ions up to= 7 are displayed in full detail. It was found that close to the dissociation threshold, the eliminationof one neutral benzene monomer is the favored process, leading to an ionized cluster of size n- 1. The efficiencyof the metastable decay of the benzene dimer ion has been measured as a function of two-photonenergy. From the resulting breakdown graph the first purely experimentalvalue of the binding energy of the benzene dimer and a value for the binding energy of the benzene dimer cation have been obtained.