Effect of surfactants on single bubble sonoluminescence behavior and bubble surface stability.
The effect of surfactants on the radial dynamics of a single sonoluminescing bubble has been investigated. Experimentally, it is observed that an increase in the surfactant concentration leads to a decline in the oscillation amplitude and hence light emission intensity. Numerical simulations support this result, showing that under the driving pressures required to achieve single bubble sonoluminescence (SBSL), the surface properties, namely, the surface elasticity and dilatational viscosity, contribute to the damping of the radial amplitude in the bubble oscillation. In most cases this stabilizes the bubble surface, and contributes to a decreased light intensity. A stronger driving pressure is necessary to achieve equivalent light emission to a surfactant-free bubble. However, as the driving pressure is increased, the surface stability also decreases, making it practically very difficult for a bubble to achieve high SBSL intensities in concentrated surfactant solutions. Although more stable owing to more mild pulsations, the instability mechanism for a surfactant-coated bubble at higher ambient radii is more likely to be of the Rayleigh-Taylor type than that of a clean bubble at the same given acoustic parameters, which can lead to bubble disintegration before correcting mechanisms can bring the bubble back into the stable sonoluminescence regime.
Department of Chemical and Biomolecular Engineering, The University of Melbourne, VIC 3010, Australia and Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
Thomas
T
Leong
National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
Kyuichi
K
Yasui
National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560, Japan.
Kazumi
K
Kato
Department of Chemical and Biomolecular Engineering, The University of Melbourne, VIC 3010, Australia.
Dalton
D
Harvie
School of Chemistry, The University of Melbourne, VIC 3010, Australia and Chemistry Department, King Abdulaziz University, Jeddah, Saudi Arabia.
Muthupandian
M
Ashokkumar
Department of Chemical and Biomolecular Engineering, The University of Melbourne, VIC 3010, Australia.
Sandra
S
Kentish