Visualizing Progressive Atomic Change in the Metal Surface Structure Made by Ultrafast Electronic Interactions in an Ambient Environment

Abstract

Understanding the atomic and molecular phenomena occurring in working catalysts and nanodevices requires the elucidation of atomic migration originating from electronic excitations. The progressive atomic dynamics on metal surface under controlled electronic stimulus in real time, space, and gas environments are visualized for the first time. By in situ environmental transmission electron microscopy, the gas molecules introduced into the biased metal nanogap could be activated by electron tunneling and caused the unpredicted atomic dynamics. The typically inactive gold was oxidized locally on the positive tip and field‐evaporated to the negative tip, resulting in the atomic reconstruction on the negative tip surface. This finding of a tunneling‐electron‐attached‐gas process will bring new insights into the design of nanostructures such as nanoparticle catalysts and quantum nanodots and will stimulate syntheses of novel nanomaterials not seen in the ambient environment.

Electrochemistry under confinement

“…A well-known problem for nanogap production is the so called electric migration, where metal atoms of the nanogap electrode migrate in the electric field in line with the flowing current, leading to a merging event of the confining walls. 136 Naitoh et al used electronic migration to form 2 nm gaps between Au electrodes. 130 They observed the gap shrinkage by measuring the transferred current between both electrodes as conductivity strongly increases with decreasing electrode distance.…”