Hot spot conditions during cavitation in water
Hot spot conditions during cavitation in water
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DOI：
10.1021/ja9844635
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发表时间：
1999-06-23
影响因子：
15
通讯作者：
Suslick, KS
中科院分区：
文献类型：
--
作者：
Didenko, YT;McNamara, WB;Suslick, KS
高强度超声波辐照的液体会发生声空化--气泡的形成、增长和内爆破裂.当气泡在声场的压缩阶段中剧烈坍塌时，在声场的稀疏阶段中气泡生长期间存储的能量被释放，作为声学噪声、冲击波、化学反应和光的发射（声致发光，SL）。[1]这种剧烈的坍缩预计会在气泡内产生一个数千开尔文的热点，[1-5]但是，迄今为止，只有有限数量的实验测量这个热点的温度。6-10尽管人们已经对水的SL进行了50多年的研究，但11-13水空化期间的有效热点温度仍然没有得到解决。鉴于水空化的重要性（超声和超声的生物效应，水污染物的声化学修复，声化学的合成应用等14），我们决定将我们以前对非水液体SL的光谱分析应用于掺杂有少量烃的水溶液。我们已经收集和分析了激发态C2 MBSL（多泡声致发光，光发射从云的空化气泡）光谱从水中的有机液体的混合物在20 kHz，并找到一个有效的发射温度为4300（200 K.为了探测空化气泡内的条件在水中，第一个要求是找到基板，将产生足够强的C2发射的分析。此外，基质必须在非常低的浓度下导致排放，以便不改变气泡在纯水中经历的运动。为此，收集以下有机基质的稀水溶液的MBSL光谱作为C2形成的前体：戊烷、环己烷、苯、乙醇、叔丁醇和丙酮。所有底物均导致弱C2
Liquids irradiated with high-intensity ultrasound undergo acoustic cavitationsthe formation, growth, and implosive collapse of bubbles. The energy stored during the growth of the bubble in the rarefaction phase of the acoustic field is released when the bubble violently collapses in the compression phase of the acoustic field, as acoustic noise, shock waves, chemical reactions, and the emission of light (sonoluminescence, SL). 1 This violent collapse is predicted to generate a hot spot of thousands of Kelvin within the bubble, 1-5 but, to date, there have been only a limited number of experimental measurements of the temperature of this hot spot. 6-10 Although the SL of water has been studied for more than 50 years, 11-13 the effective hot spot temperature during aqueous cavitation remains unresolved. Given the importance of aqueous cavitation (sonography and bioeffects of ultrasound, sonochemical remediation of aqueous pollutants, synthetic applications of sonochemistry, etc. 14), we decided to apply our previous spectroscopic analysis of SL of nonaqueous liquids to aqueous solutions doped with small amounts of hydrocarbons. We have collected and analyzed excited-state C2 MBSL (multibubble sonoluminescence, light emission from the clouds of cavitating bubbles) spectra from mixtures of organic liquids in water at 20 kHz and find an effective emission temperature of 4300 (200 K.To probe the conditions inside cavitation bubbles in water, the first requirement was to find substrates that would yield sufficiently intense C2 emission for analysis. In addition, the substrate must lead to emission at very low concentrations so as not to change the motion of the bubble from that experienced in pure water. To this end, MBSL spectra were collected for dilute aqueous solutions of the following organic substrates as precursors for C2 formation: 15 pentane, cyclohexane, benzene, ethanol, tert-butyl alcohol, and acetone. All of the substrates led to weak C2