A SONOLUMINESCING AIR BUBBLE MAY CONSIST CHIEFLY OF ARGON, William Moss of Livermore (wmoss@llnl.gov) reported at last week's Acoustical Society of America meeting. In sonoluminescence (SL), an air bubble collapses to produce ultrashort flashes of light. Recently, a German-US team proposed that the nitrogen and oxygen molecules in the hot collapsing air bubble dissociate into chemically reactive atoms which perform a mass exodus prior to the light flash; the atoms form products in the fluid surrounding the bubble, leaving behind only argon and water vapor to produce the light. (D. Lohse, Phys. Rev. Lett., 17 Feb.) Employing a rigorous fluid dynamics simulation originally developed for imploding fusion pellets, the Livermore model calculates a light spectrum for a sonoluminescing bubble of pure argon which closely matches the experimental spectrum for a collapsing air bubble, confirming and clarifying the results of earlier experiments which produced SL in air and argon. (Science, 30 May; lay-language paper at the ASA World Wide Press Room.)