Abstract
we have observed an orange emission during multi-bubbles sonoluminescence (MBSL) measurements in Kr saturated water at 1 MHz. The orange emission was observed only with the transducer, which has a partly peeled ground electrode by cavitation erosion. We confirmed the electric fields leaking from the damaged surface of the transducer. The spectrum of the orange emission showed a broad component, whose intensity gradually increased towards the near-infrared region with peaks at about 710 and 810 nm. The results of spectral measurements suggest that the origin of the emission is vibration-rotation transitions of water molecules. The charge induction by the electric fields leaked from the transducer and the charged droplet model are plausible explanation of the emission mechanism.
