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

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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