Grinolds Michael S, Lobastov Vladimir A, Weissenrieder Jonas, Zewail Ahmed H
Physical Biology Center for Ultrafast Science and Technology, California Institute of Technology, Pasadena, CA 91125, USA.
Proc Natl Acad Sci U S A. 2006 Dec 5;103(49):18427-31. doi: 10.1073/pnas.0609233103. Epub 2006 Nov 27.
Reported here is direct imaging (and diffraction) by using 4D ultrafast electron microscopy (UEM) with combined spatial and temporal resolutions. In the first phase of UEM, it was possible to obtain snapshot images by using timed, single-electron packets; each packet is free of space-charge effects. Here, we demonstrate the ability to obtain sequences of snapshots ("movies") with atomic-scale spatial resolution and ultrashort temporal resolution. Specifically, it is shown that ultrafast metal-insulator phase transitions can be studied with these achieved spatial and temporal resolutions. The diffraction (atomic scale) and images (nanometer scale) we obtained manifest the structural phase transition with its characteristic hysteresis, and the time scale involved (100 fs) is now studied by directly monitoring coordinates of the atoms themselves.
本文报道了利用具有空间和时间分辨率的4D超快电子显微镜（UEM）进行直接成像（和衍射）。在UEM的第一阶段，可以通过使用定时的单电子包获得快照图像；每个包都没有空间电荷效应。在这里，我们展示了以原子尺度空间分辨率和超短时间分辨率获得快照序列（“电影”）的能力。具体而言，结果表明，利用这些获得的空间和时间分辨率可以研究超快金属-绝缘体相变。我们获得的衍射（原子尺度）和图像（纳米尺度）显示了具有特征滞后的结构相变，并且现在通过直接监测原子本身的坐标来研究其中涉及的时间尺度（100飞秒）。
