Excited-state absorption of excitons confined in spherical quantum dots

The excited-state photoabsorption spectrum by an electron and a hole confin ed in spherical quantum dots is calculated. As the dot size is reduced, the calculated absorption peak shifts to the high-energy side, and splits into two peaks in the limit of strong confinement. This splitting represents th e changeover of the quantum size effect of the zero-dimensional excitons. O ur theoretical result is in agreement with experimental data for the transi ent infrared absorption spectra under size-selective excitation observed fo r CuCl nanocrystals embedded in Nacl crystals. [S0163-1829(99)07415-9].