Structural Analysis of Single Nanoparticles in Liquid by Low-dose STEM Nanodiffraction

Abdelali Khelfa, Caroline Byun, Jaysen Nelayah, Guillaume Wang, Christian Ricolleau, and Damien Alloyeau, 2019
exploded view of liquid cell holder TEM
Image courtesy of Protochips

Abstract

Liquid-cell TEM has enabled an interdisciplinary community of scientists to carry out atomic- / nano-scale studies of solid/liquid interfaces. Nevertheless, the restricted resolution of TEM in liquid media and the necessity to reduce the electron dose to avoid harmful radiolytic effects induced by the beam have limited the use of high resolution imaging to study the atomic structure of nanomaterials in liquid. Here we show that STEM nanodiffraction can be exploited in liquid-cell TEM experiments to overcome these two limitations. We evidence that this technique allows quick analysis of the structure of single gold nanoparticles whatever their zone axis orientation, which substantially increases the percentage of analysable nanostructures with respect to HRTEM investigations. Moreover, STEM nanodiffraction can also be used in very low dose conditions. The electron dose irradiating the analyzed nanostructures during data acquisition can be reduced by almost four orders of magnitude compared to conventional HRTEM analysis. Finally, dynamical analyses in reciprocal space are used to provide new insights into the shape-dependent rotation of nanocrystals in the liquid-cell.

Impact Statement

STEM nanodiffraction is a technique which enables rapid acquistion of diffraction patterns of nanomaterials, which is ideal for dynamic and beam sensitive samples imaged using liquid phase electron microscopy. STEM-Nanodiffraction reconstructions of gold nanorods in water were obtained and compared with high-resolution TEM (HRTEM) images of the same sample. STEM-nanodiffraction provided several advantages for liquid-phase EM studies, namely the fast acquisition time is ideal for dynamic samples, atomic resolution did not require that the particles be on zone axis, and the electron doses required were much lower than that of HRTEM.