Sonophotoluminescence from aqueous and non-aqueous solutions

The sonoluminescence generated in air-saturated aqueous and non-aqueous sol utions using 515 kHz ultrasound has been used to vibronically excite severa l fluorescent solutes, namely fluorescein, eosin, pyranine and pyrene. Emis sion, referred to as sonophotoluminescence', was generated in situ with emi ssion spectra that closely matched those obtained by direct photoexcitation of the solutes by an external light source. In the case of pyranine, exper iments were also conducted in the presence of the surfactant, sodium dodecy l sulphate (SDS). The presence of 1 mM SDS enhances the sonoluminescence an d sonophotoluminescence signals above that seen in pure water by a factor o f about 2. Pyrene sonophotoluminescence was observed in ethylene glycol. Th e emission was quenched by the addition of I-, providing good evidence that emission was from pyrene in bulk solution and not within, or on the surfac e of cavitation bubbles. (C) 1999 Elsevier Science B.V. All rights reserved .