Electronic states of free clusters and microcrystals by the selective-excitation time-resolved and space-resolved spectroscopies

结果总结如下：(1)在密闭的稀有气体气氛中，通过设置合适的气体蒸发条件，在蒸发源上方产生了两个垂直分离良好的碱金属（Li、Na、K、Rb和Cs）蒸气区。蒸发开始后，通过时间分辨和空间分辨测量获得了碱原子、二聚体和簇的消光光谱。利用激光选择性地激发各区域内的蒸汽种类，并测量了其发射光谱。将部分观测光谱与理论光谱进行了比较，得到了以下几点信息：研究了气体蒸发法中碱金属（Li, Na， K，Rb和Cs）团簇和微晶体的生长、光学生长、价电子集体模式共振的尺寸变化趋势、碱蒸气种类之间的激发能传递和蒸气区结构；(2)定向良好的半导体…在氩气流中高速热蒸发产生了更多（CdS,ZnSe, CuCl, CuBr, Ge, PbS,AgBr, Agl）微晶体束。随着蒸发的进行，结晶尺寸增大。在蒸发过程中，测量了微晶体光束的光吸收（消光）和光致发光光谱，以及沉积在衬底上的微晶体的光谱，作为蒸发开始后经过时间的函数。结果显示了激子和载流子的量子互补效应。(3)气体蒸发法制备反铁磁体（MnF_2、Rb_2MnCl_4和CsMnBr_3）微晶。在蒸发过程中，测量了微晶体光束的光吸收（消光）和光致发光光谱，以及沉积在衬底上的微晶体的光吸收（消光）光谱，作为蒸发开始后经过时间的函数。结果显示了激子和自旋波的量子约束和边缘效应。少

The results are summarized as follows.(1) two vertically well separated zones of alkali metal (Li, Na, K,Rb and Cs) vapors were produced above the evaporation source in a confined noble gas atmosphere by setting an appropriate condition for the gas evaporation. Optical extinction spectra of alkali atoms, dimers and clusters were obtained by time-resolved and space-resolved measurements after the beginning of the evaporation. Also, vapor species in each zone were selectively excited by using laser light and the emission spectra were measured. Some of the observed spectra were compared with theoretical ones, and information on the following points was derived : the growth of alkali-metal (Li, Na, K,Rb and Cs) -clusters and microcrystals and optical sgrowth in the gas evaporation method, the size trend of the collective mode resonance of the valence electrons, the excitation energy transfer between alkali vapor species and the structure of the vapor zone,(2) well-directional semiconductor … More (CdS,ZnSe, CuCl, CuBr, Ge, PbS,AgBr, Agl) microcrystal beams were produced by the thermal evaporation in argon gas stream with a high velocity. The crystallite size increases with progressing the evaporation. During the evaporation, the light absorption (extinction) and photoluminescence spectra ofthe microcrystal beams were measured, together with the those of the microcrystals depositing on asubstrate, as a function of the time elapsed after the beginning of the evaporation. The results show the quantum comfinement effects of excitons and carriers.and(3) antiferromagnet (MnF_2, Rb_2MnCl_4 and CsMnBr_3) microcrystals were produced by the gas evaporation method. During the evaporation, the light absorption (extinction) and photoluminescence spectra of the microcrystal beams were measured, together with the those of the microcrystals depositing on a substrate, as a function of the time elapsed after the beginning of the evaporation. The results show the quantum comfinement and edge effects of excitons and spin waves. Less