Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA.
Nat Chem. 2013 May;5(5):395-402. doi: 10.1038/nchem.1622. Epub 2013 Apr 14.
The advancement of techniques that can probe the behaviour of individual nanoscopic objects is of paramount importance in various disciplines, including photonics and electronics. As it provides images with a spatiotemporal resolution, four-dimensional electron microscopy, in principle, should enable the visualization of single-nanoparticle structural dynamics in real and reciprocal space. Here, we demonstrate the selectivity and sensitivity of the technique by visualizing the spin crossover dynamics of single, isolated metal-organic framework nanocrystals. By introducing a small aperture in the microscope, it was possible to follow the phase transition and the associated structural dynamics within a single particle. Its behaviour was observed to be distinct from that imaged by averaging over ensembles of heterogeneous nanoparticles. The approach reported here has potential applications in other nanosystems and those that undergo (bio)chemical transformations.
在包括光子学和电子学在内的各个领域，能够探测单个纳米物体行为的技术的进步至关重要。由于它提供了具有时空分辨率的图像，因此原则上，四维电子显微镜应该能够可视化单个纳米颗粒在实空间和倒易空间中的结构动力学。在这里，我们通过可视化单个孤立的金属有机骨架纳米晶体的自旋交叉动力学来证明该技术的选择性和敏感性。通过在显微镜中引入一个小孔，可以跟踪单个粒子内的相变和相关结构动力学。观察到其行为与通过对异质纳米粒子的集合体进行平均化成像的行为明显不同。这里报道的方法在其他纳米系统和经历（生物）化学转化的系统中有潜在的应用。
