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Plasma formation and temperature measurement during single-bubble cavitation

机译:单泡空化过程中的等离子体形成和温度测量

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摘要

Single-bubble sonoluminescence (SBSL1-5) results from the extreme temperatures and pressures achieved during bubble compression; calculations have predicted(6,7) the existence of a hot, optically opaque plasma core(8) with consequent bremsstrahlung radiation(9,10). Recent controversial reports(11,12) claim the observation of neutrons from deuterium - deuterium fusion during acoustic cavitation(11,12.) However, there has been previously no strong experimental evidence for the existence of a plasma during single- or multi-bubble sonoluminescence. SBSL typically produces featureless emission spectra(13) that reveal little about the intra-cavity physical conditions or chemical processes. Here we report observations of atomic (Ar) emission and extensive molecular (SO) and ionic (O-2(+)) progressions in SBSL spectra from concentrated aqueous H2SO4 solutions. Both the Ar and SO emission permit spectroscopic temperature determinations, as accomplished for multi-bubble sonoluminescence with other emitters(14-16). The emissive excited states observed from both Ar and O-2(+) are inconsistent with any thermal process. The Ar excited states involved are extremely high in energy (> 13 eV) and cannot be thermally populated at the measured Ar emission temperatures (4,000 - 15,000 K); the ionization energy of O-2 is more than twice its bond dissociation energy, so O-2(+) likewise cannot be thermally produced. We therefore conclude that these emitting species must originate from collisions with high-energy electrons, ions or particles from a hot plasma core.
机译:单气泡声致发光(SBSL1-5)是由于气泡压缩过程中达到的极端温度和压力所致。计算已经预测到(6,7)存在热的,光学不透明的等离子体核(8),并随之产生致辐射(9,10)。最近有争议的报道(11,12)声称在声空化过程中观察到氘-氘融合的中子(11,12。)。然而,以前没有强有力的实验证据表明单泡或多泡中存在等离子体声致发光。 SBSL通常会产生无特征的发射光谱(13),几乎看不到腔内的物理条件或化学过程。在这里,我们从浓H2SO4水溶液的SBSL光谱中报告了原子(Ar)发射以及广泛的分子(SO)和离子(O-2(+))进程的观察结果。 Ar和SO发射都允许光谱温度测定,这是与其他发射器进行多泡声致发光的结果(14-16)。从Ar和O-2(+)观察到的发射激发态与任何热处理都不一致。所涉及的Ar激发态具有极高的能量(> 13 eV),并且在测得的Ar发射温度(4,000-15,000 K)时不能被热填充。 O-2的电离能是其键解离能的两倍以上,因此O-2(+)同样无法热产生。因此,我们得出结论,这些发射物质必须源自与热等离子体核中的高能电子,离子或粒子的碰撞。

著录项

  • 来源
    《Nature》 |2005年第7029期|p. 52-55|共4页
  • 作者

    Flannigan DJ; Suslick KS;

  • 作者单位

    Univ Illinois, Dept Chem, Urbana, IL 61801 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 自然科学总论;
  • 关键词

    SONOLUMINESCING BUBBLE; EMISSION; ARGON;

    机译:声光起泡;发射;氩气;

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