In Situ Imaging of Ion Motion in a Single Nanoparticle: Structural Transformations in Selenium Nanoparticles

Abstract

Intraparticle ion motions are critical to the structure and properties of nanomaterials, but rarely disclosed. Herein, in situ visualization of ion motions in a single nanoparticle is presented by dark-field microscopy imaging, which shows HgCl 2 -induced structural transformation of amorphous selenium nanoparticles (SeNPs) with the main composition of Se 8 . Owing to the high binding affinity with selenium and coulomb interactions, Hg 2 + ions can permeate into the interior of SeNPs, making the amorphous Se 8 turn to polycrystalline Hg 3 Se 2 Cl 2 . As a proof of concept, SeNPs then serve as a highly effective scavenger for selective removal of Hg 2 + ions from solution. This new finding offers visual proof for the photophysical process involving intraparticle ion motion, demonstrating that tracking the ion motions is a novel strategy to comprehend the formation mechanism with the purpose of developing new nanostructures like nanoalloys and nano metal compounds.

The Accurate Imaging of Collective Gold Nanorods with a Polarization-Dependent Dark-Field Light Scattering Microscope

“…In recent years, dark-field microscopic (DFM) imaging has found wide applications in analytical detection 1−4 and realtime monitoring 5−9 due to its high spatial resolution, which has reached the single-particle level. 10 For example, our group has achieved the detection of biomarkers 11 and the real-time monitoring of the ion motion-induced structural transformations 12 with plasmonic nanoparticles as dark-field light scattering probes. 11,13 Plasmonic nanoparticles display a wide range of colorful images under DFM, depending on their sizes, morphologies, compositions, 14 and surrounding environments.…”

“…In recent years, dark-field microscopic (DFM) imaging has found wide applications in analytical detection − and real-time monitoring − due to its high spatial resolution, which has reached the single-particle level . For example, our group has achieved the detection of biomarkers and the real-time monitoring of the ion motion-induced structural transformations with plasmonic nanoparticles as dark-field light scattering probes. , Plasmonic nanoparticles display a wide range of colorful images under DFM, depending on their sizes, morphologies, compositions, and surrounding environments. , Furthermore, the anisotropic nanomaterials are able to present polarization-dependent dark-field light scattering, which is much different from the isotropic nanoparticles . For instance, as one-dimensional nanomaterials, anisotropic gold nanorods (AuNRs) exhibit colorful dark-field light scattering, which depends on the polarization angles. , This polarization anisotropy of a single AuNR has been widely used as orientation sensors , and analytical sensors. ,, At present, most reports focus on a single AuNR, but multiple AuNRs are distributed at random in the general solution; thus, the orientation information is not so controllable for DFM imaging.…”