Non-Boltzmann Population Distributions during Single-Bubble Sonoluminescence

Tb(III) line intensities in multibubble sonoluminescence

We observed the line emissions of trivalent terbium [Tb(III)] ions during multibubble sonoluminescence (MBSL) in the aqueous solutions of terbium chloride (TbCl₃) under argon gas atmosphere. The line intensities of excited Tb(III) ions increased with TbCl₃ concentration(mass percentage) in aqueous solutions. This phenomenon was interpreted qualitatively by numerically computing the Tb(III) line intensities in one sonoluminescing bubble among the cavitation bubbles in a liquid. The driving pressure for this sonoluminescing bubble was obtained by numerically solving the cavitation dynamic equation and bubble-pulsation equation. The Tb(III) ion line intensities obtained from the sonoluminescing bubble were attained by solving computing fluid dynamics equations and the spectral radiation formula.

Spectroscopic measurement of electronic temperature in the bubbles during single- and multibubble sonoluminescence of metal carbonyl solutions and nanodispersed suspensions

It is for the first time that we have obtained emission-line spectra of metal atoms during single-bubble sonoluminescence of metal carbonyl W(CO)₆, Mo(CO)₆, Cr(CO)₆ solutions in dodecane and similar spectra during single- and multibubble sonoluminescence of nanodispersed Cr(CO)₆ suspensions in water, 83% H₂SO₄ and 74% H₃PO₄. Nanodispersed suspensions with an average particle size of 15-20 nm were obtained through sonodispersing and filtering Cr(CO)₆ crystals in water. The method for comparing the intensities of two atomic metal lines made it possible to measure the electronic temperatures achieved in cavitation bubbles under different modes of sonolysis that vary in the range of (4.5-16)·10³ K depending on the mode of sonolysis, the type of liquid and saturating gas (He, Ar, Kr) and the acoustic energy entering the solution or suspension. The electronic temperature for multibubble sonoluminescence is, on the average, by (2-2.5)·10³ K less than for single-bubble sonoluminescence for all liquids in question.

Use of NH (A3Π–X3Σ−) sonoluminescence for diagnostics of nonequilibrium plasma produced by multibubble cavitation

The sonoluminescence spectrum of an aqueous ammonia solution allows the characterization of the nonequilibrium plasma produced by multibubble cavitation.