Na emission and bubble instability in single-bubble sonoluminescence

• Published in: Ultrasonics sonochemistry 2017-09, Vol.38, p.154-160
• Main Authors: Choi, Pak-Kon, Takumori, Keisuke, Lee, Hyang-Bok
• Format: Article
• Language: English
• Subjects: Bubble instability; High-speed shadowgraphy; Multibubble sonoluminescence; Na spectrum; Single-bubble sonoluminescence
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2017.03.015

•A Na spectrum was obtained in single-bubble sonoluminescence from SDS solution containing a dissolved noble gas.•Bubble shadowgraphs showed that Na emission originated from a dancing bubble.•Comparison with a MBSL spectrum showed different conditions at collapse. Na emission in single-bubble sonoluminescence (SBSL) was observed from 0.1mM sodium dodecyl sulfate (SDS) solution containing a dissolved noble gas at a low acoustic pressure, at which a continuous spectral component was negligible. High-speed shadowgraph movies were captured at a frame rate of 30,000fps, which indicated that bubble dancing is responsible for the Na emission. The measured bubble path length was well correlated with the Na intensity. The disintegration of a daughter bubble followed by immediate coalescence was frequently observed, which may have been the cause of the bubble dancing. A comparison of the Na spectra obtained in SBSL and multibubble SL showed that the conditions under which Na emission is generated are twofold. A narrow component was observed in the Na spectrum in SBSL, while narrow and broad components were observed in MBSL.