High spatiotemporal-resolution imaging in the scanning transmission electron microscope.

The temporal resolution in scanning transmission electron microscopy (STEM) is limited by scanning system of an electron probe, leading to only a few frames per second (fps) at most in the current microscopes. This situation enforces us to stay atomic-resolution STEM imaging and spectroscopy in the state of static observations. To push the boundary of atomic-resolution STEM imaging into dynamic observations, an unprecedentedly faster scanning system combined with fast electron detection systems should be prerequisite. Here we develop a new scanning probe system with the acquisition time of 83 nanoseconds per pixel and the fly-back time of 35 microseconds, leading to 25 fps STEM imaging with the image size of 512 × 512 pixels that is faster than a human perception speed. Using such high-speed probe scanning system, we have demonstrated the observations of shape-transformation of Pt nanoparticle and Pt single atomic motions on TiO2 (110) surface at atomic-resolution with the temporal resolution of 40 milliseconds. The present probe scanning system opens the door to use atomic-resolution STEM imaging for in-situ observation of materials dynamics under the temperatures of cooling or heating, the atmosphere of liquid or gas, electric-basing or mechanical test.