Femtosecond X-ray diffraction maps field-driven charge dynamics in ionic crystals.
Femtosecond X-ray diffraction maps field-driven charge dynamics in ionic crystals.
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飞秒 X 射线衍射图谱显示离子晶体中场驱动的电荷动力学
DOI：
10.1039/c4fd00026a
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发表时间：
2014
影响因子：
3.4
通讯作者：
A. Borgschulte
中科院分区：
文献类型：
--
作者：
M. Woerner;M. Holtz;V. Juvé;T. Elsaesser;A. Borgschulte
X射线衍射提供了对晶体中电子电荷分布的深入了解。通过在固定条件下记录和分析大量的衍射峰，以高的空间分辨率确定了平衡电子分布。相反，结构变化过程中和之后的瞬态电子密度主要是未知的。最近，我们引入了飞秒X射线粉末衍射从多晶样品，以确定瞬态电子密度图的空间分辨率为0.03 nm和时间分辨率为100 fs。在泵浦-探测方法与激光驱动的桌面硬X射线源，光学诱导的结构变化的时间解决衍射的硬X射线探测脉冲在不同的时间延迟从激发的粉末样品和记录高达几十个反射同时。在晶格中的原子排列的时间依赖性的变化，以及修改的电子密度来自衍射数据。作为一个典型的场驱动过程，我们在这里解决的准瞬时变化的电子密度在LiBH 4，LiH和NaBH 4在响应于非共振强光场。LiBH 4和NaBH 4中的光致电荷迁移表现出从阴离子（BH−4）到相应阳离子的电子转移。LiBH_4中BH_4四面体的扭曲几何形状导致H原子对电子转移的不同贡献。LiH显示从Li到H的电荷转移，即，在强电场的存在下LiH的电离度的增加。这种意想不到的行为起源于强电子相关LiH是显而易见的，从准粒子能带结构的库仑空穴加屏蔽交换（COHSEX）形式主义内计算的比较。
X-Ray diffraction provides insight into the distribution of electronic charge in crystals. Equilibrium electron distributions have been determined with high spatial resolution by recording and analysing a large number of diffraction peaks under stationary conditions. In contrast, transient electron densities during and after structure-changing processes are mainly unknown. Recently, we have introduced femtosecond X-ray powder diffraction from polycrystalline samples to determine transient electron density maps with a spatial resolution of 0.03 nm and a temporal resolution of 100 fs. In a pump–probe approach with a laser-driven tabletop hard X-ray source, optically induced structure changes are resolved in time by diffracting the hard X-ray probe pulses at different time delays from the excited powder sample and recording up to several tens of reflections simultaneously. Time-dependent changes of the atomic arrangement in the crystal lattice as well as modified electron densities are derived from the diffraction data. As a prototypical field-driven process, we address here quasi-instantaneous changes of electron density in LiBH4, LiH and NaBH4 in response to a non-resonant strong optical field. The light-induced charge relocation in LiBH4 and NaBH4 exhibits an electron transfer from the anion (BH−4) to the respective cation. The distorted geometry of the BH4 tetrahedron in LiBH4 leads to different contributions of the H atoms to electron transfer. LiH displays a charge transfer from Li to H, i.e., an increase of the ionicity of LiH in the presence of the strong electric field. This unexpected behavior originates from strong electron correlations in LiH as is evident from a comparison with quasi-particle bandstructures calculated within the Coulomb-hole-plus-screened-exchange (COHSEX) formalism.
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影响因子：
4.4
作者：
Elsaesser, T.;Woerner, M.
通讯作者：
Woerner, M.
影响因子：
64.8
作者：
Schultze, Martin;Bothschafter, Elisabeth M.;Krausz, Ferenc
通讯作者：
Krausz, Ferenc
Si 基态性质的从头 Hartree-Fock 赝势方法
DOI：
--
发表时间：
1985
期刊：
影响因子：
--
作者：
I. Ohkoshi
通讯作者：
I. Ohkoshi
由强光场诱导的 LiBH4 虚拟量子态中的电子转移，并通过飞秒 X 射线衍射绘制。
影响因子：
8.6
作者：
J. Stingl;F. Zamponi;B. Freyer;M. Woerner;T. Elsaesser;A. Borgschulte
通讯作者：
A. Borgschulte
DOI：
10.1209/epl/i2003-00562-1
发表时间：
2003-08-01
期刊：
EUROPHYSICS LETTERS
影响因子：
--
作者：
Lebègue, S;Alouani, M;Pickett, WE
通讯作者：
Pickett, WE