Abstract
Intense orange Na^* emission was observed in different spatial locations from blue emission during multibubble sonoluminescence in sulfuric acid. The color change from blue to orange observed along the streamer in the filamentous structure of a bubble cloud. By stroboscopic observation, the Na^* emission seemed to occur when a large bubble ejected tiny bubbles toward a pressure node after bubble coalescence around a pressure antinode. Comparing a high resolution Na^* spectrum of sulfuric acid with water, the full width at half maximum of the spectra were almost the same, where the estimations of the temperature and pressure inside the bubbles were 3300K and 390atm. The intensity of Na^* emission in sulfuric acid increased at lower frequency in contrast to the water case.
