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

主要研究结果如下：(1)通过设定合适的蒸发条件，在受限稀有气体气氛中，在蒸发源上方形成了两个垂直分布良好的碱金属(Li、Na、K、Rb、Cs)蒸发区。在蒸发开始后，通过时间分辨和空间分辨测量获得了碱原子、二聚体和团簇的光学消光光谱。用激光选择性地激发了各区域的水蒸气物种，并测量了发射光谱。将观测到的一些光谱与理论值进行了比较，得出了以下几点的信息：(2)气相蒸发法中碱金属(Li，Na，K，Rb，Cs)团簇和微晶的生长及光学生长，价电子集体模共振的大小趋势，碱蒸气物种之间的激发能量转移和蒸汽区的结构，(2)定向半导体…在高速的Ar气流中热蒸发产生了更多的(Cd，ZnSe，CuCL，CuBr，Ge，PbS，AgBr，Agl)微晶束。随着蒸发过程的进行，微晶尺寸逐渐增大。在蒸发过程中，测量了微晶束的光吸收(消光)和光致发光光谱，以及沉积在衬底上的微晶体的吸收(消光)和光致发光光谱，作为蒸发开始后经过的时间的函数。结果表明激子和载流子的量子补偿效应。(3)用气相蒸发法制备了反铁磁体(MnF_2、Rb_2MnCl_4和CsMnBr3)微晶。在蒸发过程中，测量了微晶束的光吸收(消光)和光致发光光谱，以及沉积在衬底上的微晶体的吸收(消光)和光致发光光谱，作为蒸发开始后经过的时间的函数。结果表明激子和自旋波的量子压缩和边缘效应。较少

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