J.R. Macdonald Laboratory, Physics Department, Kansas State University, Manhattan, Kansas 66506-2604, USA.
Phys Rev Lett. 2012 Dec 7;109(23):233002. doi: 10.1103/PhysRevLett.109.233002. Epub 2012 Dec 5.
Recently, using midinfrared laser-induced electron diffraction (LIED), snapshots of a vibrating diatomic molecule on a femtosecond time scale have been captured [C.I. Blaga et al., Nature (London) 483, 194 (2012)]. In this Letter, a comprehensive treatment for the atomic LIED response is reported, a critical step in generalizing this imaging method. Electron-ion differential cross sections (DCSs) of rare gas atoms are extracted from measured angular-resolved, high-energy electron momentum distributions generated by intense midinfrared lasers. Following strong-field ionization, the high-energy electrons result from elastic rescattering of a field-driven wave packet with the parent ion. For recollision energies ≥100 eV, the measured DCSs are indistinguishable for the neutral atoms and ions, illustrating the close collision nature of this interaction. The extracted DCSs are found to be independent of laser parameters, in agreement with theory. This study establishes the key ingredients for applying LIED to femtosecond molecular imaging.
最近，使用中红外激光诱导电子衍射（LIED），已经捕捉到了一个在飞秒时间尺度上振动的双原子分子的快照[C.I. Blaga 等人，《自然》（伦敦）483,194（2012）]。在这封信中，报道了一种原子 LIED 响应的综合处理方法，这是推广这种成像方法的关键步骤。从强中红外激光产生的测量的角分辨、高能电子动量分布中提取了稀有气体原子的电子-离子微分截面（DCS）。在强场电离之后，高能电子是由与母离子的弹性再散射产生的场驱动波包。对于再碰撞能量≥100 eV，中性原子和离子的测量 DCS 无法区分，说明了这种相互作用的紧密碰撞性质。提取的 DCS 被发现与激光参数无关，这与理论相符。这项研究为将 LIED 应用于飞秒分子成像确立了关键要素。
