Barke Ingo, Hartmann Hannes, Rupp Daniela, Flückiger Leonie, Sauppe Mario, Adolph Marcus, Schorb Sebastian, Bostedt Christoph, Treusch Rolf, Peltz Christian, Bartling Stephan, Fennel Thomas, Meiwes-Broer Karl-Heinz, Möller Thomas
Institute of Physics, University of Rostock, Universitätsplatz 3, 18055 Rostock, Germany.
IOAP, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.
Nat Commun. 2015 Feb 4;6:6187. doi: 10.1038/ncomms7187.
The diversity of nanoparticle shapes generated by condensation from gaseous matter reflects the fundamental competition between thermodynamic equilibration and the persistence of metastable configurations during growth. In the kinetically limited regime, intermediate geometries that are favoured only in early formation stages can be imprinted in the finally observed ensemble of differently structured specimens. Here we demonstrate that single-shot wide-angle scattering of femtosecond soft X-ray free-electron laser pulses allows three-dimensional characterization of the resulting metastable nanoparticle structures. For individual free silver particles, which can be considered frozen in space for the duration of photon exposure, both shape and orientation are uncovered from measured scattering images. We identify regular shapes, including species with fivefold symmetry and surprisingly large aspect ratio up to particle radii of the order of 100 nm. Our approach includes scattering effects beyond Born's approximation and is remarkably efficient-opening up new routes in ultrafast nanophysics and free-electron laser science.
由气态物质凝聚产生的纳米颗粒形状的多样性反映了在生长过程中热力学平衡与亚稳态构型持久性之间的基本竞争。在动力学受限的情况下，仅在早期形成阶段受到青睐的中间几何形状可以印刻在最终观察到的不同结构样本的集合中。在这里，我们证明了飞秒软X射线自由电子激光脉冲的单次广角散射能够对所得的亚稳态纳米颗粒结构进行三维表征。对于单个自由银颗粒，在光子曝光期间可将其视为在空间中冻结，通过测量的散射图像可以揭示其形状和取向。我们识别出规则形状，包括具有五重对称性且纵横比惊人地大的物种，其颗粒半径可达100纳米左右。我们的方法包括超越玻恩近似的散射效应，并且效率显著，为超快纳米物理学和自由电子激光科学开辟了新途径。
