Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, Leiden, The Netherlands.
Huygens-Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Leiden University, Niels Bohrweg 2, Leiden, The Netherlands; IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, New York 10598, USA.
Ultramicroscopy. 2021 Mar;222:113199. doi: 10.1016/j.ultramic.2020.113199. Epub 2021 Jan 7.
Transmission electron microscopy at very low energy is a promising way to avoid damaging delicate biological samples with the incident electrons, a known problem in conventional transmission electron microscopy. For imaging in the 0-30 eV range, we added a second electron source to a low energy electron microscopy (LEEM) setup, enabling imaging and spectroscopy in both transmission and reflection mode at nanometer (nm) resolution. The latter is experimentally demonstrated for free-standing graphene. Exemplary eV-TEM micrographs of gold nanoparticles suspended on graphene and of DNA origami rectangles on graphene oxide further establish the capabilities of the technique. The long and short axes of the DNA origami rectangles are discernable even after an hour of illumination with low energy electrons. In combination with recent developments in 2D membranes, allowing for versatile sample preparation, eV-TEM is paving the way to damage-free imaging of biological samples at nm resolution.
在极低能量下进行透射电子显微镜是一种很有前途的方法，可以避免用入射电子破坏生物样品的精细结构，这是传统透射电子显微镜中的一个已知问题。为了在 0-30 eV 的范围内成像，我们在低能电子显微镜 (LEEM) 装置中添加了第二个电子源，从而能够以纳米 (nm) 的分辨率在透射和反射模式下进行成像和光谱分析。后者在独立的石墨烯上进行了实验验证。悬浮在石墨烯上的金纳米粒子和石墨烯氧化物上的 DNA 折纸矩形的典型 eV-TEM 显微照片进一步确立了该技术的能力。即使在低能电子照射一个小时后，DNA 折纸矩形的长轴和短轴仍然可以分辨。与最近在二维膜方面的发展相结合，该技术允许进行灵活的样品制备，为在纳米分辨率下对生物样品进行无损伤成像铺平了道路。
