ELECTRONIC STATES OF SNI4 SINGLE-CRYSTALS AND ITS CLUSTERS INSERTED IN THE MOLECULAR VESSELS OF CYCLODEXTRINS

From the reflection spectra of SnI4 single crystal, the exciton absorp tion band has been observed at peak energies, 3.13 eV (1.6 K) and 3.07 eV (room temperature). The binding energy of the exciton is estimated to be 350 meV (1.6 K) assuming the hydrogen-like series for the excit on energy levels. The novel idea of using a cyclodextrin molecule as a size-controlling vessel to make a SnI4 cluster is proposed. The refle ction spectra of SnI4 clusters inserted in alpha-, beta- and gamma-cyc lodextrins were measured. The first exciton absorption peak of the clu sters shifts to the higher energy by nearly 0.3 eV (1.6 K) and 0.4 eV (room temperature) compared with that of the single crystals. The shif t is due to the quantum size effect.