Olshin Pavel K, Bongiovanni Gabriele, Drabbels Marcel, Lorenz Ulrich J
Laboratory of Molecular Nanodynamics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland.
Nano Lett. 2021 Jan 13;21(1):612-618. doi: 10.1021/acs.nanolett.0c04184. Epub 2020 Dec 10.
Atomic-resolution electron microscopy is a crucial tool to elucidate the structure of matter. Recently, fast electron cameras have added the time domain to high-resolution imaging, allowing static images to be acquired as movies from which sample drift can later be removed computationally and enabling real-time observations of atomic-scale dynamics on the millisecond time scale. Even higher time resolution can be achieved with short electron pulses, yet their potential for atomic-resolution imaging remains unexplored. Here, we generate high-brightness microsecond electron pulses from a Schottky emitter whose current we briefly drive to near its limit. We demonstrate that drift-corrected imaging with such pulses can achieve atomic resolution in the presence of much larger amounts of drift than with a continuous electron beam. Moreover, such pulses enable atomic-resolution observations on the microsecond time scale, which we employ to elucidate the crystallization pathways of individual metal nanoparticles as well as the high-temperature transformation of perovskite nanocrystals.
原子分辨率电子显微镜是阐明物质结构的关键工具。最近,快速电子相机为高分辨率成像增添了时域维度,使得静态图像能够以电影形式采集,随后可通过计算去除样本漂移,并实现对毫秒时间尺度上原子尺度动力学的实时观测。利用短电子脉冲可实现更高的时间分辨率,但其在原子分辨率成像方面的潜力尚未得到探索。在此,我们通过肖特基发射极产生高亮度微秒级电子脉冲,我们短暂地将其电流驱动至接近极限。我们证明,与连续电子束相比,使用此类脉冲进行漂移校正成像在存在大量漂移的情况下仍可实现原子分辨率。此外,此类脉冲能够在微秒时间尺度上进行原子分辨率观测,我们利用这一点阐明了单个金属纳米颗粒的结晶途径以及钙钛矿纳米晶体的高温转变过程。