Optical properties of selenium clusters/particles incorporated into porousmaterials

We have investigated the optical properties of Se clusters/particles incorp orated into porous glasses as well as into zeolites in order to explore the effect of geometrical constraints on the electronic states of Se. It has b een found that the optical gap E-0, of Se shifts to higher energy in porous glasses, depending on the pore diameter D; Delta E-0 proportional to D-0.5 . The observation indicates that carriers in extended (nonlocalized) states of amorphous Se are not simply confined in zero dimension as the pore size decreases, but are confined and/or localized in the unique geometrical por e structure. On the other hand, the electronic slates of Se clusters in zeo lites are modulated by the absence of inter-molecular (ring or chain) inter action, and are influenced by the interaction between lone pair electrons o f Se and cations of the framework of zeolites.