论文标题
超快电子波包成型的散射 - 对称控制
Scattering-asymmetry control with ultrafast electron wave packet shaping
论文作者
论文摘要
通过原子散射紧密聚焦的电子束，形成了现代电子显微镜的基础之一。当目标原子从梁中心移动时，就会发生基本的对称性破裂。这种位移导致梁的偏转和散射电子的不对称角分布。在这里，我们提出了一个概念，以通过在Atto-toto-picsecend Time尺度上的动量空间中塑造入射的高能电子波包来控制散射不对称的符号和大小。塑形控制波数据包的超快实空动力学，从而在影响参数依赖性量子干扰的两个相互竞争贡献与波数据包在目标上的动量分布之间转移了平衡。我们发现弹性散射在波数据包性能上的敏感性很强，这种效应为超快电子显微镜提供了有希望的新途径。
Scattering of a tightly focused electron beam by an atom forms one of the bases of modern electron microscopy. A fundamental symmetry breaking occurs when the target atom is displaced from the beam center. This displacement results in a deflection of the beam and an asymmetric angular distribution of the scattered electrons. Here we propose a concept to control the sign and magnitude of the scattering asymmetry by shaping the incident high-energy electron wave packet in momentum space on the atto- to picosecond time scale. The shaping controls the ultrafast real-space dynamics of the wave packet, shifting the balance between two competing contributions of the impact-parameter-dependent quantum interference and the momentum distribution of the wave packet on the target. We find a strong sensitivity of the elastic scattering on the wave packet properties, an effect that opens promising new avenues for ultrafast electron microscopy.
