Development of a Neutral Atom Microscope

各种类型的显微镜广泛应用于科学研究、医学和工业。能够看到肉眼看不到的小物体，对于表征材料、制造和法医科学至关重要。科学研究和技术方面的新能力是通过开发分辨率和灵敏度更高的新型显微镜来实现的。该项目将探索使用聚焦原子束以纳米级分辨率探测表面的方法。这解决了原子物理学的长期目标，即制造一种中性原子显微镜，类似于电子显微镜，但具有不同的化学灵敏度和较小的破坏性相互作用。一种改进的聚焦原子束的方法将使用脉冲磁透镜来实现。这种原子像差校正透镜将使研究团队能够开创中性原子显微镜的应用。像差的校正对于光学显微镜的性能是非常重要的，并且使电子显微镜具有原子尺度的分辨率。原子像差校正透镜的突破将使原子光刻技术和具有分子分辨率的中性原子显微镜的操作取得进展。从事该项目的学生将接受原子物理、原子光学和表面化学研究方法的培训，这将有助于他们为进入大学和高科技行业的职业生涯做准备。该项目将开发的显微镜的原理是将处于激发亚稳态的中性霓原子聚焦到表面。在每个原子的撞击后，一个电子被发射出来，并进行能量分析，提供表面化学成分的独特指纹。图像将通过对表面上的原子进行栅格扫描来获得。研究小组将使用脉冲电磁线圈作为透镜，对原子进行磁性成像。这使得脉冲高电流导线可以在原子束上施加短暂而强烈的聚焦场，从而利用高折射功率，而不会使原子在进入和离开透镜时受到边缘场的影响。像差校正将通过使透镜向前变得更窄来实现，从而对速度较快的原子施加更大的力。脉冲透镜与脉冲超音速光束很好地匹配，脉冲超音速光束产生非常明亮的亚稳态霓虹原子束。该团队已经建造了一个工作原型，并计划实施光束增亮和速度选择的方法。有了这些改进，预计分辨率将优于10 nm。原子透镜的进一步发展将解决残留像差问题。与此同时，该小组将使用分析系统开发亚稳态撞击电子显微镜。将这两项发展结合起来，将能够展示具有纳米级分辨率的中性原子显微镜。

Microscopes of various types are widely used in scientific research, medicine, and industry. The ability to see objects that are too small to see with the naked eye is crucial for characterizing materials, for manufacturing, and for forensic science. New capabilities in scientific research and technology are enabled by developing novel new microscopes with enhanced resolution and sensitivity. This project will explore ways to use focused atom beams to probe surfaces with nanometer-scale resolution. This addresses the longstanding goal in atomic physics of making a neutral atom microscope, similar to an electron microscope, but with different chemical sensitivity and less destructive interactions. An improved method to focus atom beams will be implemented using a pulsed magnetic lens. This aberration-corrected lens for atoms will enable the research team to pioneer applications for a neutral-atom microscope. The correction of aberrations is tremendously important for the performance of optical microscopes, and has enabled atomic scale resolution for electron microscopes. A breakthrough in aberration-corrected lenses for atoms will enable advances in atom lithography and the operation of a neutral atom microscope with molecular resolution. Students working on this project will gain training in atomic physics, atom optics, and surface chemistry research methods, and this will help prepare them for careers in universities and high tech industries.The principle of the microscope to be developed in this project is that neutral neon atoms in an excited metastable state are focused to a surface. After the impact of each atom, an electron is emitted which is energy-analyzed, providing a unique fingerprint of the chemical composition of the surface. The image will be acquired by rastering the atoms across the surface. The research team will use a pulsed electromagnetic coil as a lens for magnetic imaging of atoms. This allows for pulsed, high-current wires to exert a brief, strong focusing field on an atomic beam, taking advantage of the high refractive power without subjecting the atoms to fringing fields as they enter and leave the lens. Aberration correction will be achieved by tapering the lens to be narrower towards the front, thereby applying a greater force to the faster atoms. The pulsed lens is well-matched to a pulsed supersonic beam which produces a very bright beam of metastable neon atoms. The team has constructed a working prototype and plans to implement methods of beam brightening and velocity selection. With these improvements, a resolution better than 10 nm is expected. Further developments of the atomic lens will address residual aberrations. In parallel, the group will develop metastable impact electron microscopy using an analyzer system. Combining the two developments will enable demonstration of a neutral atom microscope with nanoscale resolution.