Papers by Keyword: Sonoluminescence

Abstract: Light emission in sound-irradiated liquids, known as Sonoluminescence (SL), is associated with the phenomenon of cavitation that affects wafer damage during megasonic processing of wafers. It has been shown that the intensity of SL can be substantially decreased through the dissolution of carbon dioxide in deionized water. However, such dissolution decreases the pH to roughly 4.0, which is not very desirable for the removal of contaminant particles. This paper reports two chemical systems that are capable of taking advantage of the effect of CO₂ while allowing the use of slightly higher pH values. Specifically, NH₄OH/CO₂ and NH₄HCO₃/dilute HCl systems have been shown to be capable of well controlled reduction in SL at pH 5.7 or 7.0. In order to test whether the free radical scavenging ability of CO₂ may be responsible for its strong SL-inhibitory effect, the effect of a well known free radical scavenger, dimethyl sulfoxide (DMSO), on SL produced in DI water has been investigated.

Abstract: An improved fundamental understanding of the megasonic cleaning process is necessary to optimize cleaning efficiency and minimize the unwanted damage to fragile structures. Argon sonoluminescence (SL) measurements are done to achieve an improved insight in the collapse threshold and behavior of microbubbles. This paper reports on acoustic cavitation by means of Ar Sonoluminescence (SL) investigation achieved with a dedicated test cell, a photomultiplier tube (PMT) and a gasification system. The results show an increase in SL signal as a function of the applied acoustic power density. An increase in Ar concentration results in a decrease in SL signal. Furthermore, a clear hysteretic behavior in the SL signal is identified when ramping the acoustic power up and down. This hysteresis effect can be attributed to the nucleation of bubbles during the increasing branch of the power loop. Finally the time evolution of SL light after the switching on of the acoustic transducers revealed the existence of a delay time.