利用准弹性中子散射研究金属氧化物团簇内部碳链的动态

Study on the dynamics of the polymer chain confined in metal oxide cluster by quasielastic neutron scattering

中子散射技术是研究凝聚态物质和材料性质的重要手段。通过将碳链植入金属氧化物团簇分子的内部,可以实现对碳链运动的彻底改变。通过分析中子谱得知,这些金属氧化物团簇分子内部的碳链的大尺度空间平移运动几乎被完全限制,碳链上的甲基和亚甲基的转动速度也被大幅度减慢。另外,碳链上的不同碳原子的运动有不均匀性。这些现象都表明,金属氧化物团簇分子对于其内部的高分子运动有强约束效应。该效应在金属氧化物团簇的包裹行为上有决定性作用。

Background： Metal oxide clusters are very important inorganic materials, which are widely used in catalytic reactions. And neutron scattering is an important technique for the study of the condensed matters and materials. Purpose： The aim is to study the dynamics of the polymer chain confined in metal oxide cluster molecules. Methods： Quasielastic neutron scattering technique is employed to measure the dynamics of the sample. A theoretical model, which assumes that the vibrational, translational and rotational motions are independent of each other, is used to analyze the neutron spectra. Results： The dynamics of the polymer chain confined in metal oxide cluster are highly restricted in space. The large-scale motion of the chain is greatly hindered. The rotations of the methyl group and methylene group are also slowed down. Conclusion： The metal oxide cluster exhibits ultra-confinement effect on the polymer chains.