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Research on Electronic States in Clusters

团簇电子态研究

基本信息

批准号：
59460030
负责人：
TOSHIHIRO ARAI
金额：
$ 4.8万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1984
资助国家：
日本
起止时间：
1984 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-59460030/
关键词：
microcluster cluster,Quasi-microcluster microcrustal quari-crystal intrinsic absorption edge surface effect

项目摘要

The apparatus which was constructed from two vaccum rooms and a diffrerntial pumping system was bulided up to make a cluster veam and to measure some optical properties of clusters in the beam. Vaporization of sample was accomplished an electron gun in small Cu-botttle which had a various shaped nozzle. Small cluster beam was introduced into another vacuum room, in which a pair of 30cm-long parallel mirrors was settled for measurements of potical absorption, optical scattering and optical emission etc. This room also apparatus for collecting od clusters. According to result of preliminary experiment on Ag-cluster beam, the plasma absorption was not observed. The size dependence of photoluminescence of CdSe cluster which was gathered from a cooled substrate was measured. The two lines originating exciton and donor-acceptor pair, respectively, were observed in large size clysters. However, the intensity of excition line decreased with decreasing cluster size and the line could be hardly … More observed in cluster size less then 4nm in diameter. This phenomenon is interpreted to be due to the inelastic scattering of the electron in surface zone of cluster. The small size cluster had zincblend structure instead of wurtzite structure in bulk. It may originate from increase of the ratio of the surface to volume. Size dependences of relaxation mechanism of optically excited electrons in CdS clusters were also investigated by means of photoacoustic and Iuminescence spectroscopy. Non-radiative recombination rate increases with decreasing cluster size. One of the member has worked on hydrogenrated Si microcrystalline film by taking second derivative modes of infrared absorption. Two absorption peaks due to SiH on Si(111) and Si (110) surfaces of the mycrocrystalline grains in the film, respectively, near 2100 cm ^<-1> were clarified and the presence of both the symmetric and asymmetric modes of stretching in SiH_2 on Si(100) and SiH_3 on Si(111) and Si(110) surfaces was assigned successfully. Further, one of the member has studied theoretically on the structure of a quasi-crystal. A 3-D penrose transformation is found. The expansion rates <tau> in linear dimension and <tau>^9 in volume, are by far the larger than <tau> and <tau>^3 respectively ever believed. The transformation decides only the skeleton uniquely, leavin some other degrees of freedom undecicded. It strikinglydiffers from deterministic 2-D case. Many other properties are common with the 2-D case. This transformation is helpful in under standing the quasi-crystal structure. Less

该装置由两个真空室和一个差动泵浦系统组成，用于形成簇束并测量束中簇的一些光学特性。样品的蒸发是通过小铜瓶中的电子枪完成的，该铜瓶具有各种形状的喷嘴。将小团簇光束引入另一个真空室，真空室中放置一对30cm长的平行镜，用于测量光吸收、光散射和光发射等。该室还有收集小团簇的装置。根据银团簇束的初步实验结果，没有观察到等离子体吸收。测量了从冷却的基底收集的 CdSe 簇的光致发光的尺寸依赖性。在大尺寸灌肠中观察到分别源自激子和供体-受体对的两条线。然而，激发线的强度随着团簇尺寸的减小而降低，并且在直径小于4nm的团簇尺寸中很难观察到激发线。这种现象被解释为由于团簇表面区域电子的非弹性散射所致。小尺寸团簇具有闪锌矿结构而不是块状纤锌矿结构。它可能源于表面积与体积之比的增加。还通过光声和发光光谱研究了 CdS 团簇中光激发电子弛豫机制的尺寸依赖性。非辐射复合率随着簇尺寸的减小而增加。其中一名成员利用红外吸收的二阶导数模式研究了氢化硅微晶薄膜。薄膜中微晶粒的Si(111)和Si(110)表面上分别在2100 cm^-1附近的两个SiH吸收峰被澄清，并且成功地确定了Si(100)表面上的SiH_2和Si(111)和Si(110)表面上的SiH_3中对称和不对称拉伸模式的存在。此外，其中一位成员还对准晶体的结构进行了理论研究。发现了 3-D 彭罗斯变换。线性尺寸的膨胀率 <tau> 和体积的膨胀率 <tau>^9 分别远大于人们所认为的 <tau> 和 <tau>^3。变换仅唯一决定骨架，而未决定其他一些自由度。它与确定性二维情况显着不同。许多其他属性对于二维情况是常见的。这种转变有助于理解准晶体结构。较少的