title: Effects of argon sparging rate, ultrasonic power, and frequency on multibubble sonoluminescence spectra and bubble dynamics in NaCl aqueous solutions.
abstract: The sonoluminescence spectra from acoustic cavitation in aqueous NaCl solutions are systematically studied in a large range of ultrasonic frequencies under variation of electrical power and argon sparging. At the same time, bubble dynamics are analysed by high-speed imaging. Sodium line and continuum emission are evaluated for acoustic driving at 34.5, 90, 150, 365, and 945kHz in the same reactor vessel. The results show that the ratio of sodium line to continuum emission can be shifted by the experimental parameters: an increase in the argon flow increases the ratio, while an increase in power leads to a decrease. At 945kHz, the sodium line is drastically reduced, while the continuum stays at elevated level. Bubble observations reveal a remarkable effect of argon in terms of bubble distribution and stability: larger bubbles of non-spherical shapes form and eject small daughter bubbles which in turn populate the whole liquid. As a consequence, the bubble interactions (splitting, merging) appear enhanced which supports a link between non-spherical bubble dynamics and sodium line emission.
authors.affiliation: Christian Doppler Laboratory for Cavitation and Micro-Erosion, Drittes Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany. Electronic address: ccairos@physik3.gwdg.de.
authors.forename: Carlos
authors.initials: C
authors.lastname: Cairós
authors.affiliation: Christian Doppler Laboratory for Cavitation and Micro-Erosion, Drittes Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Schneider
authors.affiliation: Institut de Chimie Séparative de Marcoule, ICSM-UMR5257 CNRS/CEA/UM2/ENSCM, BP17171, 30207 Bagnols-sur-Ceze Cedex, France.
authors.forename: Rachel
authors.initials: R
authors.lastname: Pflieger
authors.affiliation: Christian Doppler Laboratory for Cavitation and Micro-Erosion, Drittes Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Mettin
keywords: Bubble dynamics; High-speed imaging; Multibubble sonoluminescence; Sodium line emission