QUANTUM-SIZE EFFECTS ON THE EXCITON EXCITED-STATES OF CUCL NANOCRYSTALS

We have investigated infrared transient absorption at 77 K, which appe ars under size-selective excitation of 1S excitons in CuCl nanocrystal s embedded in NaCl matrices. The transient absorption is mainly ascrib ed to the optical transition between the 1S to 2P exciton states in Cu Cl nanocrystals. The peak energy of the transient absorption band incr eases by about 200 meV with the decrease in the crystal size from more than 10 nm down to 1.4 nm in effective radii, while the width of the band increases by more than 100 meV. These facts indicate that the qua ntum size effect on the exciton excited state is much deviated from th e exciton confinement regime and the hydrogen-like P exciton component s are widely distributed among the various excited confinement states split by the quantum size effect. (C) 1998 Elsevier Science B.V. All r ights reserved.