Diffraction and microscopy with attosecond electron pulse trains
Diffraction and microscopy with attosecond electron pulse trains
复制标题
DOI：
10.1038/s41567-017-0007-6
复制
发表时间：
2018-03-01
期刊：
影响因子：
19.6
通讯作者：
Baum, Peter
中科院分区：
文献类型：
--
作者：
Morimoto, Yuya;Baum, Peter
阿秒光谱学（1-7）可以直接在时间上解析电子过程，但是电影般的时空记录受到太长的波长（类似于原子距离的100倍）或再碰撞技术中的源-样品纠缠的阻碍（8-11）。在这里，我们通过使用自由空间电子而不是高次谐波光子（1-7）或重新碰撞波包（8-11），将阿秒计量推进到皮米波长和亚原子分辨率。一束70 keV、4.5 pm德布罗意布罗意波长的电子束被激光周期的电场调制成具有亚光周期持续时间的电子脉冲序列。晶体硅的时间分辨衍射揭示了< 10-as的布拉格发射延迟，并证明了分析阿秒-埃衍射的可能性。实空间电子显微镜以亚光周期分辨率可视化光波在空间和时间中的传播方式。这种阿秒科学与电子显微镜和衍射的统一使光驱动过程的时空成像在电子显微镜可以访问的整个样品形态范围内成为可能。
Attosecond spectroscopy(1-7) can resolve electronic processes directly in time, but a movie-like space-time recording is impeded by the too long wavelength (similar to 100 times larger than atomic distances) or the source-sample entanglement in re-collision techniques(8-11). Here we advance attosecond metrology to picometre wavelength and sub-atomic resolution by using free-space electrons instead of higher-harmonic photons(1-7) or re-colliding wavepackets(8-11). A beam of 70-keV electrons at 4.5-pm de Broglie wavelength is modulated by the electric field of laser cycles into a sequence of electron pulses with sub-optical-cycle duration. Time-resolved diffraction from crystalline silicon reveals a < 10-as delay of Bragg emission and demonstrates the possibility of analytic attosecond-angstrom diffraction. Real-space electron microscopy visualizes with sub-light-cycle resolution how an optical wave propagates in space and time. This unification of attosecond science with electron microscopy and diffraction enables space-time imaging of light-driven processes in the entire range of sample morphologies that electron microscopy can access.