Helium clusters and droplets: microscopic superfluidity and other quantum effects†
Helium clusters and droplets: microscopic superfluidity and other quantum effects†
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DOI：
10.1080/00268976.2013.802039
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发表时间：
2013-07
影响因子：
1.7
通讯作者：
J. Toennies
中科院分区：
文献类型：
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作者：
J. Toennies
在过去的18年里，通过一些新颖的实验，唯一的天然超流体元素氦的许多微观性质已经变得可用。小氦团簇的物质波衍射证实了二聚体的异常大的键距（5.2 nm）和极弱的结合能（10−7 eV）以及小氦团簇的其他奇异性质。对附着在小簇上或嵌入在大超流体液滴中的闭壳发色团分子的高分辨率光谱研究表明，由于超流动性，分子几乎没有摩擦旋转，并且微观超流动性只需要少量He原子。液滴内原子和分子的无摩擦平动也被观察到。这些实验和其他一些实验表明，氦滴是所有低温基质中最温和、最冷的，在未来的广泛应用中具有巨大的潜力。
Many microscopic properties of the only natural superfluid element helium have become available within the last 18 years through a number of novel experiments. The diffraction of matter-waves of small helium clusters has established the unusually large bond distance (5.2 nm) and extremely weak binding energy (10−7 eV) of the dimer and other exotic properties of small helium clusters. The high-resolution spectroscopy of closed-shell chromophore molecules attached to small clusters or embedded inside large superfluid droplets have revealed that as a result of superfluidity, molecules rotate virtually without friction and that only a handful of He atoms are required for microscopic superfluidity. The frictionless translational motion of atoms and molecules inside the droplets has also been observed. These and a number of other experiments demonstrate that helium droplets are the most gentle and coldest of all cryomatrices with enormous potential for a wide range of future applications.