Research on Electronic States in Clusters

用两个真空室和一个差压抽气系统组成了一个装置，用来制作团簇束流，并测量团簇束流中的一些光学性质。样品的蒸发是用装有各种形状喷嘴的小铜瓶的电子枪完成的。小团簇束流被引入另一个真空室，在该真空室中放置了一对30厘米长的平行反射镜，用于测量团簇的光吸收、光散射和光发射等，该真空室也是收集团簇的装置。根据对银团簇束流的初步实验结果，没有观察到等离子体吸收。测量了从冷却的衬底上收集的CdSe团簇的光致发光的尺寸依赖性。在大尺寸灌肠器中观察到两条分别来自激子和施主-受主对的谱线。但是，随着团簇尺寸的减小，激发线的强度降低， ...更多信息 在直径小于4 nm的团簇中观察到。这种现象被解释为电子在团簇表面区的非弹性散射。小尺寸团簇的整体结构由纤锌矿结构转变为锌共混物结构。这可能源于表面积与体积比的增加。利用光声光谱和荧光光谱研究了CdS团簇中光激发电子弛豫机制的尺寸依赖性。非辐射复合率随团簇尺寸的减小而增大。其中一位研究人员利用红外吸收的二阶导数模式对氢化硅微晶薄膜进行了研究。在2100 cm ~ 2附近，明确了SiH在薄膜中微晶颗粒Si（111）和Si（110）表面上的两个吸收峰<-1>，并成功地归属了Si（100）表面上SiH_2和Si（111）和Si（110）表面上SiH_3的对称和非对称伸缩模。此外，其中一名成员从理论上研究了准晶体的结构。发现了一个三维彭罗斯变换，<tau>其线性膨胀率和<tau>体积膨胀率分别比人们所认为的大得多<tau><tau>。该变换只唯一地确定了骨架，而不确定其他自由度。它与确定性的二维情形有显著的不同。许多其他属性与二维情况相同。这种变换有助于理解准晶体结构。少

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