Institut für Physik, Universität Rostock, Rostock, Germany.
Max Planck Institute for Solid State Research, Stuttgart, Germany.
Nature. 2023 Jan;613(7945):662-666. doi: 10.1038/s41586-022-05577-1. Epub 2023 Jan 25.
Field emission of electrons underlies great advances in science and technology, ranging from signal processing at ever higher frequencies to imaging of the atomic-scale structure of matter with picometre resolution. The advancing of electron microscopy techniques to enable the complete visualization of matter on the native spatial (picometre) and temporal (attosecond) scales of electron dynamics calls for techniques that can confine and examine the field emission on sub-femtosecond time intervals. Intense laser pulses have paved the way to this end by demonstrating femtosecond confinement and sub-optical cycle control of the optical field emission from nanostructured metals. Yet the measurement of attosecond electron pulses has remained elusive. We used intense, sub-cycle light transients to induce optical field emission of electron pulses from tungsten nanotips and a weak replica of the same transient to directly investigate the emission dynamics in real time. Access to the temporal properties of the electron pulses rescattering off the tip surface, including the duration τ = (53 as ± 5 as) and chirp, and the direct exploration of nanoscale near fields open new prospects for research and applications at the interface of attosecond physics and nano-optics.
电子场发射是科学和技术取得重大进展的基础，其应用范围从高频信号处理到以皮米分辨率对物质原子尺度结构进行成像。为了使电子显微镜技术能够完全可视化物质在自然空间（皮米）和时间（阿秒）尺度上的电子动力学，需要能够在亚飞秒时间间隔内限制和检查场发射的技术。强激光脉冲通过证明从纳米结构金属中进行飞秒限制和亚光周期控制的光场发射，为实现这一目标铺平了道路。然而，阿秒电子脉冲的测量仍然难以实现。我们使用强的、亚周期光瞬变来诱导从钨纳米尖端发射电子脉冲的光场发射，并用相同瞬变的弱副本实时直接研究发射动力学。电子脉冲在尖端表面上的散射的时间特性的获取，包括持续时间τ=（53 飞秒±5 飞秒）和啁啾，以及纳米级近场的直接探索，为阿秒物理和纳米光学界面的研究和应用开辟了新的前景。
