Abstract

In heavily Cu⁺-doped alkali halides, microcrystals of Cu= halides having the size less than 0.1 μm are known to be formed due to the coagulation of Cu⁺[1-3]. The present paper reports the optical properties of CuCl microcrystals (1 mol% in NaCl) in order to study the crystal size effect upon their exciton states. Figure 1 shows two exciton absorption bands, Z₃ and Z_1,2, which are located at the higher energy side with more broadened band= width compared with those in the bulk CuCl on account of the size effect: the smaller the size of the microcrystal, the larger the exciton energy [3]. Under the band-to-band excitation a broad emission band appears with the Stokes shift of ~30 meV from the Z₃-absorption band.

© 1984 Optical Society of America