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Development of methods for the analysis of physical properties of free clusters by using inner-core excitation

开发利用内核激发分析自由团簇物理性质的方法

基本信息

批准号：
16201021
负责人：
YAO Makoto
金额：
$ 32.28万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

项目摘要

We proposed a new method for measuring the electron transport in free cluster and developed a new instrument to carry out this method. The instrument consists of a 2D detector and a time of flight mass spectrometer. Both the electron ion coincidence (EICO) and the multi-hit momentum imaging (MHMI) of deep inner-core excited nano-particles were carried out by this instrument. In MHMI measurements, the charge-to-mass ratio and the momentum of fragment ions emitted from inner-core excited nano-particles are obtained from the time of flight and position of ions. An insight into the mobility of the holes can be deduced from the analysis of the momentum of fragment ions. In addition, we developed a new cluster source to produce the core-shell type ternary alloy cluster of an arbitrary composition.The EICO spectra for Ar_<99>Kr_1 clusters reveal that singly charged ions are emitted from the inner-core excited clusters in addition to the multiple charged ions. The dependence of the EICO spectra on photon energy and cluster size suggests that the holes created through vacancy cascade on the krypton atoms are transferred to the surrounding atoms, and that the singly charged ions are the primary product of the krypton photoabsorption. Charge localization is suggested for the inner-core excited mixed rare-gas clusters from the analysis of the momentum of daughter ions.We have carried out the MHMI measurements of bromophenol and bromobiphenyl. Both molecules have emitted many fragment ions as a result of inner-core excitation of bromine. The analysis of the relative abundance of multiple charged ions suggests the decrease of the charge migration from bromine atom to oxygen atom as the increase of molecular length.Our results suggest that the hard x-ray is of use to study the charge mobility of nano-particles such as clusters and single molecules.

本文提出了一种测量自由团簇电子输运的新方法，并研制了一台新的测量仪器。该仪器由一个二维探测器和一个飞行时间质谱仪组成。利用该仪器对深内核激发的纳米粒子进行了电子离子符合（EICO）和多击动量成像（MHMI）。在MHMI测量中，由离子的飞行时间和位置获得从内核激发的纳米颗粒发射的碎片离子的荷质比和动量。通过对碎片离子动量的分析，可以推断出空穴的迁移率。此外，我们还研制了一种新的团簇源，用于制备任意组成的核壳型三元合金团簇，Ar_ Kr_1团簇的EICO谱<99>表明，除了多电荷离子外，还从内核激发的团簇中发射出单电荷离子。EICO谱与光子能量和团簇尺寸的关系表明，氪原子上的空位级联产生的空穴被转移到周围的原子上，单电荷离子是氪光吸收的主要产物。从子离子动量的分析中，提出了内核激发混合稀有气体团簇的电荷局域化。由于溴的内核激发，这两种分子都发射了许多碎片离子。多电荷离子的相对丰度分析表明，随着分子长度的增加，溴原子向氧原子的电荷迁移率减小，这表明硬X射线可以用于研究团簇和单分子等纳米粒子的电荷迁移率。