Sonoluminescence effects in ZnS materials

A detailed study of sonoluminescence (SL) in ZnS bulk and powdered material s is presented. It is argued that high-frequency vibrations of dislocations in acoustic fields constitute the specific mechanism of a light production related to point defects and complexes of the defects generated by an acou stic wave. The SL spectra in bulk ZnS samples are found to originate from t he defect complex (V-Zn(-),A(c)) of a zinc vacancy and a single-charged acc eptor in a cation site. The computed energy levels are in excellent agreeme nt with the experimentally observed SL peaks at about 512, 526, 540 and 560 +/- 10 nm. The SL peak at 500 nm is suggested to arise from the radiative transitions of free electrons to the energy band formed by moving dislocati ons. The defect related emissions are partially responsible for the SL band s in powdered ZnS materials whereas the broadness of the SL spectra can be explained in the framework of radiative transitions of free electrons withi n the conduction band. Possible applications of the phenomenon of crystal S L are outlined. (C) 2000 Elsevier Science Ltd. All rights reserved.