ABSTRACT

Two convincing theories of single-bubble sonoluminescence(SBSL) are reviewed. SBSL is the light emission phenomenon from a single bubble in liquid irradiated by sufficiently strong ultrasonic wave. The light pulse is emitted at the collapse of the bubble periodically with the frequency of the ultrasonic wave. The pulse width is experimentally measured to range from 50ps to 250ps. The spectrum is broadband and can be fitted by the black-body formula with the effective temperature ranging from 6,000K to 25,000K. Shock-wave theory and hot-spot theory are reviewed as possible mechanisms of SBSL. It is recommended to measure the heated region inside the bubble experimentally to determine which theory is correct, for example by Thomson scattering of a narrow laser beam.