Title :

Atomic and Electronic Structure of Ultrathin Single-crystalline Nanowires from Electron Microscopy and Simulations

Abstract :

Being the eye of nanomaterials space with atomic-scale resolution, aberration-corrected (scanning) transmission electron microscopy (AC-(S)TEM) can provide a wealth of structural information in low-dimensional materials. With a judicious choice of system of interest, atomistic simulations can facilitate such microscopy. In this talk, I will discuss a couple of such simulation-aided microscopy experiments for different inorganic nanowires.

The talk will focus on structural aspect of symmetry-broken single-crystalline ultrathin Au nanowires, wherein simulations predict that the {111} atomic planes of Au undergo wrinkling, leading to formation of saddle surfaces. Detailed AC-TEM on such wires confirms this prediction. Crystallographic arguments pinpoint the nature of surface stress to be the driving factor behind such structural transformation. Recent AC-STEM experiments with similar scale Pt nanowires show that with a priori crystallographic information, it is possible to reconstruct a 3-D structure from a single projection image of the material, paving a way for suitable alternative to conventional electron tomography. Lastly, in terms of electronic properties, I will briefly talk about Te nanowires, wherein simple adsorption of NO2 shows a semiconductor to metal transition- predicted in simulations and verified by experiments.