Rupp Daniela, Flückiger Leonie, Adolph Marcus, Gorkhover Tais, Krikunova Maria, Müller Jan Philippe, Müller Maria, Oelze Tim, Ovcharenko Yevheniy, Röben Benjamin, Sauppe Mario, Schorb Sebastian, Wolter David, Mitzner Rolf, Wöstmann Michael, Roling Sebastian, Harmand Marion, Treusch Rolf, Arbeiter Mathias, Fennel Thomas, Bostedt Christoph, Möller Thomas
IOAP, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany.
ARC Centre of Excellence for Advanced Molecular Imaging, La Trobe University, Bundoora, Victoria 3086, Australia.
Phys Rev Lett. 2016 Oct 7;117(15):153401. doi: 10.1103/PhysRevLett.117.153401.
We studied the nanoplasma formation and explosion dynamics of single large xenon clusters in ultrashort, intense x-ray free-electron laser pulses via ion spectroscopy. The simultaneous measurement of single-shot diffraction images enabled a single-cluster analysis that is free from any averaging over the cluster size and laser intensity distributions. The measured charge state-resolved ion energy spectra show narrow distributions with peak positions that scale linearly with final ion charge state. These two distinct signatures are attributed to highly efficient recombination that eventually leads to the dominant formation of neutral atoms in the cluster. The measured mean ion energies exceed the value expected without recombination by more than an order of magnitude, indicating that the energy release resulting from electron-ion recombination constitutes a previously unnoticed nanoplasma heating process. This conclusion is supported by results from semiclassical molecular dynamics simulations.
我们通过离子光谱学研究了超短、强X射线自由电子激光脉冲中单个大型氙团簇的纳米等离子体形成和爆炸动力学。单次衍射图像的同步测量实现了单团簇分析，该分析不受团簇尺寸和激光强度分布的任何平均影响。测量得到的电荷态分辨离子能谱显示出窄分布，其峰值位置与最终离子电荷态呈线性比例关系。这两个明显的特征归因于高效复合，最终导致团簇中主要形成中性原子。测量得到的平均离子能量比无复合情况下预期的值高出一个多数量级，表明电子 - 离子复合产生的能量释放构成了一个此前未被注意到的纳米等离子体加热过程。这一结论得到了半经典分子动力学模拟结果的支持。
