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Title: Collision Broadening Of Line Spectrum In Sonoluminescence

The direct measurement of temperature inside a sonoluminescing bubble as it is at its flashing phase is almost impossible due to the smallness of the bubble and the short duration of the flashing. One may estimate the temperature through fitting the continuum spectrum of sonoluminescence by the black body radiation formula, or fitting the shape of atomic or molecular line spectrum (the different temperature, density and pressure result in the different shape of the line spectrum due to the effect of collision broadening). However, the temperature changes in a huge range at short duration as the bubble flashes, therefore, the observed spectra are some kind of average one, so are those fitted results. To evaluate the instantaneous temperature more accurately, we simulate the processes of the bubble motion and the thermodynamics inside the bubble, in which atomic or molecular line spectra with the collision broadening effect and the continuum spectra contributed from the processes of electron-atom bremsstrahlung, electron-ion bremsstrahlung and recombination radiation and radiative attachment of electrons to atoms and molecules are taken into account in calculating the light emission. If both the calculated continuum spectra and the shape of line spectra can well represent the experimental data, we maymore » deduce that the calculation of the temperature, density and pressure is reliable and we indirectly evaluate those quantities inside the bubble. In the present calculation, the line spectra of OH radical at about 310 nm mixing the electron transition with the vibration and rotational bands are considered. The calculation qualitatively consists with the observation, and we expect that with the more precise bubble dynamics model instead of the uniform model employed in the present calculation we may improve the quantitative result.« less
Authors:
 [1] ;  [1] ;  [2]
  1. Department of Physics, Tsinghua University, Beijing 100084 (China)
  2. (China)
Publication Date:
OSTI Identifier:
21148816
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1022; Journal Issue: 1; Conference: ISNA 18: 18. international symposium on nonlinear acoustics, Stockholm (Sweden), 7-10 Jul 2008; Other Information: DOI: 10.1063/1.2956181; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ACOUSTICS; ATOMS; BLACKBODY RADIATION; BREMSSTRAHLUNG; BUBBLES; ELECTRON ATTACHMENT; ELECTRON COLLISIONS; ELECTRONS; HYDROXYL RADICALS; IONS; LINE BROADENING; LUMINESCENCE; MOLECULES; NONLINEAR PROBLEMS; RECOMBINATION; ROTATIONAL STATES; TEMPERATURE MEASUREMENT; VIBRATIONAL STATES