3D Spectroscopic Tracking of Individual Brownian Nanoparticles during Galvanic Exchange

Abstract

Monitoring chemical reactions in solutions at the scale of individual entities is challenging: single particle detection requires small confocal volumes which are hardly compatible with Brownian motion, particularly when long integration times are necessary. Here, we propose a real-time (10 Hz) holography-based nm-precision 3D tracking of single moving nanoparticles. Using this localization, the confocal collection volume is dynamically adjusted to follow the moving nanoparticle and allow continuous spectroscopic monitoring. This concept is applied to the study galvanic exchange in freely-moving colloïdal silver nanoparticles with gold ions generated in-situ. While the Brownian trajectory reveals particle size, spectral shifts dynamically reveal composition changes and transformation kinetics at the single object level, pointing at different transformation kinetics for free and tethered particles.

The New Era of High-Throughput Nanoelectrochemistry

“…First, high-throughput, wide-field-of-view imaging of the electrode region allows observation of where and how nanoobjects encounter the electrode. Spatiotemporal localization of a wide variety of individual objects (from biological objects to individual particles and molecules) can be achieved with all microscopies, including those supplemented with spectroscopic interrogation, ,, in 2D or more recently in 3D . Second, the optical signal associated with the individual objects is scrutinized, as it provides further complementary information about the electrochemical transformation of the isolated object or in its surrounding environment.…”

Metal Core–Shell Nanoparticle Supercrystals: From Photoactivation of Hydrogen Evolution to Photocorrosion

“…The oxidative corrosion of the NPs may also affect the integrity of the NPs and of the SCs. For example, in the absence of Cl − ions, one expects a dissolution of the core of the Ag@Pt NPs, while in the presence of Cl − , the Ag core would be converted into a less dense AgCl, yielding a size increase of the NP [43,44] ). In the absence of Cl − ions, H 2 evolution should be associated with dissolution of NPs from the SC.…”

The new era of high throughput nanoelectrochemistry

“…Spatiotemporal localization of a wide variety of individual objects (from biological objects, to individual particles and molecules) can be achieved with all microscopies, including those supplemented with spectroscopic interrogation, 358,365,366 in 2D or more recently in 3D. 367 Second, the optical signal associated to the individual objects is scrutinized, as it provides a further complementary information about the electrochemical transformation of the isolated object or in its surrounding environment.…”