准自由硅团簇的表面模

Brief Communications Surface Phonon Modes of Quasi free Si Clusters *

文章介绍用惰性气体冷凝法制得Ｓｉ团簇并首次将其嵌入多孔硅的孔隙中，经与孔壁多次掠角散射形成准自由团簇．激光拉曼谱测量显示，除了多孔硅的散射峰（５１０ｃｍ－１附近）外，存在一些新的低频散射峰：分别在２７（２９），３７和１９５ｃｍ－１处。理论计算表明，它们来源于Ｓｉ团簇表面模ＳＡ（球面模或扭转模）或表面模与ＴＡ（Ｌ）模的组合。这些低频拉曼峰在多孔硅、硅团簇材料、单晶硅和非晶硅中均未见过．

Silicon clusters have been introduced into the skeleton of porous silicon (PS) and quasifree Si clusters formed by numerous grazing angle collisions with the inner walls of PS pores.Several new Raman peaks at 27(29),37 and 195cm -1 have been observed in addition to the main peak of PS(～510cm -1 ).Theoretical calculations indicate that these low frequency Raman peaks may be attributed to the localized surface phonon modes of the introduced Si clusters and their combination with TA modes,which have never been observed previously in PS,Si cluster based materials,c Si or a Si.