Abstract
Due to recent drastic advances in the technologies of diagnostic ultrasound scanner and microbubble contrast agent, the performance and functions of ultrasound scanner seems to be high enough for real-time 2D or 3D monitoring of microscopic phenomena. As a fundamental study for applying ultrasound scanner in such monitoring purposes, we observed sonochemical reaction fields with 7.5 MHz ultrasound probe. By using chemiluminescence (CL) intensity of luminol induced by 1 MHz ultrasound as a measure, sonochemical reaction fields were observed by changing acoustic intensity. It was found that at acoustic intensities higher than the threshold for CL, bubbles with diameter about several micrometers and several ten micrometers were observed. At an acoustic intensity slightly lower than threshold for CL, bubbles with diameters in the same range as above were also observed. Our results indicated the presence of quasi-threshold for sonochemical reactions at which microbubbles are induced but the numbers are too small for reactions.
