Information for : Imaging ultrafast molecular dynamics with laser-induced electron diffraction
Information for : Imaging ultrafast molecular dynamics with laser-induced electron diffraction
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发表时间：
2012
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通讯作者：
C. Blaga;Junliang Xu;A. DiChiara;E. Sistrunk;Kaikai Zhang;P. Agostini;T. Miller;L. DiMauro;C. Li
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作者：
C. Blaga;Junliang Xu;A. DiChiara;E. Sistrunk;Kaikai Zhang;P. Agostini;T. Miller;L. DiMauro;C. Li
激光诱导电子衍射（LIED）方法的目标是以原子尺度的空间分辨率研究共形变换下气体分子的飞秒动力学。在一个典型的泵浦-探测方案中，泵浦脉冲产生一个动态系统，然后LIED探测器将映射原子的时间相关位置。在这样的实验中，探测脉冲的持续时间定义了时间分辨率，而空间分辨率从在此期间积累的电子衍射图像中检索。在这封信中，我们报告了一种方法，允许应用一个单一的激光脉冲来询问简单的homopolysaccharide双原子分子的键长变化。我们的研究结果表明，亚埃空间分辨率（5 pm）是促进使用强长波长光源（> 1 μm）。此外，波长的变化等效于改变泵浦和探测之间的延迟。在我们的例子中，时钟是由隧道电离（泵浦）初始化的，探测器是一个场驱动的波包，它在稍后的时间（即大约一个光学周期）与母分子核心重新散射（衍射）。LIED方法连接了强场再散射物理和传统电子衍射（CED）的许多概念。本文总结了LIED中使用的实践步骤和理论工具，数据分析方法和误差评估。
The laser-induced electron diffraction (LIED) method aims at probing the femtosecond dynamics of gaseous molecules under conformal transformation with atomic-scale spatial resolution. In a typical pump-probe scheme, a pump pulse creates a dynamic system and then the LIED probe would map the time-dependent positions of atoms. In such experiment, the duration of the probe pulse defines the temporal resolution, while the spatial resolution is retrieved from the electron diffraction image accumulated during this time. In this Letter, we report on an approach that allows the application of a single laser pulse to interrogate the bond length change of simple homonuclear diatomic molecules. Our results show that sub-Angstrom spatial resolution (5 pm) is facilitated by using intense long wavelength sources (> 1 μm). In addition, variation of the wavelength is equivalent to changing the delay between pump and probe. In our case, the clock is initialized by tunnel ionization (pump) and the probe is a field-driven wave packet that rescatters (diffracts) with the parent molecular core at a later time, i.e. approximately one optical cycle. The LIED method bridges a number of concepts from strong-field rescattering physics and conventional electron diffraction (CED). This document summarizes the practical steps and theoretical tools used in LIED, the data analysis method and error assessment.