Scenario of the electric breakdown and UV radiation spectra in single-bubble sonoluminescence

In a preceding paper we put forward the hypothesis that the single-bubble s onoluminescence (SBSL) is caused by strong electric fields arising near the surface of a collapsing gas bubble on account of the flexoelectric effect in water. Here we argue that these fields can indeed provoke a multiple ele ctric breakdown in water, in a micron-size region near the surface of the c ollapsing gas bubble, and show that the main numerical characteristics of t he SBSL can be naturally explained within this mechanism. The SBSL spectra are determined by radiative transitions between high-energy levels of noble -gas atoms excited by hot electrons produced by the strong flexoelectric fi eld in "cold" water. (C) 1999 American Institute of Physics. [S0021-3640(99 )00319-9].