Computational Simulation of Ionization Processes in Single-Bubble and Multi-Bubble Sonoluminescence

Abstract

The most recent spectroscopic studies of moving-single bubble sonoluminescence (MSBSL) and multi-bubble sonoluminescence (MBSL) have revealed that hydrated electrons (e$_{\texttt{aq}}^{-}$) are generated in MSBSL but absent in MBSL. To explore the mechanism this phenomenon, we numerically simulated the ionization processes in single- and multi-bubble sonoluminescence in aqueous solution of terbium chloride (TbCl$_{3}$). The results show that the maximum degree of ionization of single-bubble sonoluminescence (SBSL) is approximately 10000 times greater than that of MBSL under certain special physical parameters. The hydrated electrons (e$_{\texttt{aq}}^{-}$) formed in SBSL are far greater than those in MBSL provided these electrons are ejected from a bubble into a liquid. Therefore, the quenching of e$_{\texttt{aq}}^{-}$ to SBSL spectrum is stronger than that of the MBSL spectrum. This may be the reason that the trivalent terbium [Tb(III)] ion line intensities from SBSL in the TbCl$_{3}$ aqueous solutions with the acceptor of e$_{\texttt{aq}}^{-}$ are stronger than those of TbCl$_{3}$ aqueous solutions without the acceptor of e$_{\texttt{aq}}^{-}$, whereas the Tb(III) ion line intensities from MBSL are not variational, which is significant for exploring the mechanism behind the cavitation and sonoluminescence.