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Molecular emission and temperature measurements from single-bubble sonoluminescence
Hangxun Xu1, Kenneth S Suslick
1School of Chemical Sciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Physical Review Letters
|September 28, 2010
Summary
Single-bubble sonoluminescence in phosphoric acid reveals strong OH radical emission. This emission acts as a spectroscopic thermometer, measuring temperatures between 6000 K and over 10,000 K.
Area of Science:
- Chemistry
- Physics
- Spectroscopy
Background:
- Single-bubble sonoluminescence (SBSL) in water typically exhibits featureless continuum emission.
- Investigating SBSL in alternative media is crucial for understanding emission mechanisms and potential applications.
Purpose of the Study:
- To investigate single-bubble sonoluminescence in phosphoric acid (H3PO4).
- To explore the potential of OH radical emission as a spectroscopic thermometer for SBSL.
Main Methods:
- Acoustically driving a single bubble in phosphoric acid.
- Analyzing the emitted spectra, specifically focusing on excited OH radicals around 310 nm.
- Fitting experimental SBSL spectra to OH A2Σ+ - X2Π rovibronic transitions to determine temperature.
Main Results:
- Observed strong molecular emission from excited OH radicals in phosphoric acid.
- Developed a method to use OH emission as a spectroscopic thermometer.
- Emission temperatures ranged from 6200 to 9500 K with varying acoustic pressure (1.9–3.1 bar).
- Temperatures ranged from 6000 to >10,000 K with different dissolved monatomic gases (He to Xe).
Conclusions:
- Single-bubble sonoluminescence in phosphoric acid produces significant OH radical emission.
- This OH emission is a viable method for spectroscopic thermometry in SBSL, capable of measuring extreme temperatures.
- The temperature is sensitive to acoustic pressure and the type of dissolved gas.
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