On the origin of sonoluminescence and sonochemistry.
نویسندگان
چکیده
Recent experimental results on the origins of sonoluminescence and sonochemistry are reviewed and the conclusion reached that most observed effects originate from thermal processes associated with a localized hot-spot created by acoustic cavitation. Sonoluminescence is definitively due to chemiluminescence from species produced thermally during cavitational collapse and is not attributable to electric microdischarge. Homogenous sonochemistry follows the behaviour expected for high temperature thermal reactions. Ultrasonic irradiation of liquids containing solid powders dramatically increases their chemical reactivity and improves chemical yields for a wide range of synthetically useful heterogenous reactions. Shock waves generated from the cavitational hot-spot cause high velocity interparticle collisions in such slurries. Brittle solids are shock fragmented, which increases surface area. This increase in reactive surface provides for substantial increases in chemical reactivity. For malleable metal powders, these collisions are sufficiently violent to remove surface oxide coatings and to induce local melting at the site of impact for most metals.
منابع مشابه
Sonochemistry and sonoluminescence in microfluidics.
One way to focus the diffuse energy of a sound field in a liquid is by acoustically driving bubbles into nonlinear oscillation. A rapid and nearly adiabatic bubble collapse heats up the bubble interior and produces intense concentration of energy that is able to emit light (sonoluminescence) and to trigger chemical reactions (sonochemistry). Such phenomena have been extensively studied in bulk ...
متن کاملExtreme conditions during multibubble cavitation: Sonoluminescence as a spectroscopic probe.
We review recent work on the use of sonoluminescence (SL) to probe spectroscopically the conditions created during cavitation, both in clouds of collapsing bubbles (multibubble sonoluminescence, (MBSL)) and in single bubble events. The effective MBSL temperature can be controlled by the vapor pressure of the liquid or the thermal conductivity of the dissolved gas over a range from ∼1600 to ∼900...
متن کاملTemperature inhomogeneity during multibubble sonoluminescence.
When a liquid is subjected to high-intensity ultrasound, bubbles are formed, grow, and implosively collapse. This phenomenon of acoustic cavitation generates both chemical reactions (i.e., sonochemistry) and the emission of light (i.e., sonoluminescence, SL). It is generally agreed that both sonochemistry and sonoluminescence result from the intense compressional heating of gas and vapor inside...
متن کاملMixture segregation within sonoluminescence bubbles
This paper concerns a relaxation of the assumption of uniform mixture composition in the interior of sonoluminescence bubbles. Intense temperature and pressure gradients within the bubble drive relative mass diffusion which overwhelms diffusion driven by concentration gradients. This thermal and pressure diffusion results in a robust compositional inhomogeneity in the bubble which lasts several...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Ultrasonics
دوره 28 5 شماره
صفحات -
تاریخ انتشار 1990