Water-molecular emission from cavitation bubbles affected by electric fields
1Department of Physics, Meiji University, 1-1-1 Higashimita, Tama-ku, Kawasaki 214-8571, Japan.
Ultrasonics Sonochemistry
|February 13, 2018
Summary
Multibubble sonoluminescence in noble gas-saturated water produced orange light. This emission, linked to electric fields from a transducer, suggests a novel mechanism involving water molecule transitions under extreme conditions.
Area of Science:
- Acoustics
- Plasma Physics
- Spectroscopy
Background:
- Sonoluminescence (SL) is light emission from collapsing bubbles.
- Multibubble sonoluminescence (MBSL) involves numerous bubbles and can produce different spectra.
- Electric fields near transducers may influence SL.
Purpose of the Study:
- To investigate the origin and spectral characteristics of orange emission in MBSL.
- To explore the role of electric fields in MBSL.
- To propose a mechanism for the observed emission.
Main Methods:
- Performing MBSL experiments in water saturated with noble gases (He, Ne, Kr) at 1 MHz.
- Utilizing a piezoceramic transducer with a peeled ground electrode.
- Analyzing the emission spectrum, focusing on the near-infrared region.
Main Results:
- Observed orange emission localized near the transducer's electrode.
- The emission spectrum showed a broad component increasing towards the near-infrared, with peaks at 713 and 813 nm.
- Spectral shape was consistent across different noble gases.
Conclusions:
- The electric fields from the transducer likely influence cavitation bubbles, causing the observed emission.
- The broad spectral component is attributed to vibration-rotation transitions of water molecules, broadened by high pressure and electric fields during bubble collapse.
- A proposed emission mechanism involves charge induction and the charged droplet model.
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