We probe in situ by synchrotron SAXS/WAXS and UV-visible spectroscopy the nucleation growth of gold nanoparticles. The use a fast-mixing stopped-flow device enables assessment whole particle formation process with 200 ms time resolution. number particles, their size distribution, yield reaction is determined real through quantitative analysis SAXS data on an absolute scale. Two ligands exhibit drastically different behaviors: when alkanoic acid used, phase 1 s followed step whose rate...

We report on the self-assembly of colloidal CdSe nanoplatelets into micrometers long anisotropic needle-like superparticles (SPs), which are formed in solution upon addition an antisolvent to a stable dispersion. Optical fluorescence microscopy, transmission electron and small-angle X-ray scattering provide detailed structural characterization show that each particle is composed 10(6) organized highly aligned columns. Within SPs, stacked other maximize contact surface between ligands. When...

In this Letter, we characterize experimentally the diffusiophoretic motion of colloids and lambda-DNA toward higher concentration solutes, using microfluidic technology to build spatially temporally controlled gradients. We then demonstrate that segregation spatial patterning particles can be achieved from temporal variations solute profile. This takes form a strong trapping potential, stemming an osmotically induced rectification mechanism time-dependent variations. Depending on symmetry...

We report the continuous lateral extension of cadmium selenide nanoplatelets into nanosheets using injection precursors at high temperature. show that we can obtain CdSe with dimensions up to 700 nm and a well-defined thickness be tuned atomic precision. When nanosheets' size increases, they roll on themselves form nanoscrolls unroll upon surface modification. The final geometry different morphologies favor growth specific crystal facets. provide detailed study its optimization for three thicknesses.

We study in detail the synthesis of CdTe nanoplatelets. Three populations nanoplatelets with a thickness defined atomic precision are obtained. show that can be extended laterally to obtain nanosheets lateral dimensions micrometer range. present reaction conditions for formation and their extension. The products analyzed optical spectroscopy, transmission electron microscopy, small-angle X-ray scattering. investigate electro-optical properties films formed nanoplatelets, we current...

The emergence of chirality is a central issue in chemistry, materials science, and biology. In nanoparticle assemblies, has been shown to arise through few different processes, but chiral organizations composed plate-like nanoparticles, class material under scrutiny due their wide applicative potential, have not yet reported. We show that ribbons stacked board-shaped cadmium selenide (CdSe) nanoplatelets (NPLs) twist upon the addition oleic acid ligand, leading reach several micrometers...

We show that colloidal nanoplatelets can self-assemble to form a 1D superlattice. When self-assembled, an additional emission line appears in the photoluminescence spectrum at low temperatures. This is collective effect, greatly enhanced when NPLs are self-assembled. It attributed longitudinal optical (LO) phonon replica of band-edge exciton, and its presence self-assembled explained using model based on efficient photons reabsorption between neighboring nanoplatelets. The temperatures...

The metal-driven self-assembly processes of a covalent polyoxometalate (POM)-based hybrid bearing remote terpyridine binding sites have been investigated. In strongly dissociating solvent, discrete metallomacrocycle, described as molecular triangle, is formed and characterized by 2D diffusion NMR spectroscopy (DOSY), small-angle X-ray scattering (SAXS), modeling. less the primary supramolecular structure, combining negatively charged POMs cationic metal linkers, further self-assemble through...

Understanding the formation mechanism of colloidal nanocrystals is paramount importance in order to design new nanostructures and synthesize them a predictive fashion. However, reliable data on pathways leading from molecular precursors are not available yet. We used synchrotron-based time-resolved situ small wide-angle X-ray scattering experimentally monitor CdSe quantum dots synthesized solution through heating up octadecene at 240 °C. Our experiment yields complete movie structure...

The accurate determination of the dimensions a nano-object is paramount to development nanoscience and technology. Here we provide procedures for sizing quasi-spherical colloidal nanocrystals (NCs) by means small-angle X-ray scattering (SAXS). Using 2.5 10 nm PbS NCs as model system, protocols outline extraction net NC SAXS pattern background correction address calibration scattered intensity an absolute scale. size distribution retrieved fitting corrected either parametrized analytical...

While initial theories on quantum confinement in colloidal dots (QDs) led to analytical band gap/size relations or sizing functions, numerical methods describe size quantization more accurately. However, because of the lack reliable researchers fit experimental data sets using models with redundant, physically meaningless parameters that break down upon extrapolation. Here, we propose a new function based proportional correction for nonparabolic bands. Using known bulk parameters, predict...

A comprehensive study of the mechanism gold nanoparticle formation has been conducted using third-generation synchrotrons. The particles were obained by reduction AuCl(3) BH(4)(-) in toluene. Gold oxidation state was monitored X-ray absorption near edge spectroscopy (XANES), while size and concentration nanoparticles assessed small-angle scattering (SAXS). time-resolution 100 ms achieved for a total time few seconds. change with amount Au(0) present solution is obtained XANES. inside from...

Colloidal CdSe nanoplatelets with monolayer control over their thickness can now be synthesized in solution and display interesting optical properties. From a fundamental point of view, the self-assembly impact properties through short-range interactions, achieving dispersion state is major relevance. The related issue colloidal stability important from an applicative standpoint perspective processing these materials. Using UV-vis spectroscopy, we assess dispersions at different nanoparticle...

The ability of thin materials to shape-shift is a common occurrence that leads dynamic pattern formation and function in natural man-made structures. However, harnessing this concept rationally design inorganic structures at the nanoscale has remained far from reach due lack fundamental understanding essential physical components. Here, we show interaction between organic ligands nanocrystal surface responsible for full range chiral shapes seen colloidal nanoplatelets. adsorption results...

The nucleation and growth of three-dimensional superlattices gold nanoparticles has been followed directly in situ by means small angle x-ray scattering. These assemblies spontaneously form a dilute solution providing the particles are large enough to generate van der Waals driven attraction sufficient counterbalance thermal energy. nucleate very soon after birth individual their kinetics is slower than predicted mechanism simple diffusion towards superlattices. first limited size (170 nm...

Diffusiophoresis, i.e. the movement of macromolecules along a molecular gradient, is shown to be an efficient means drive particles in microchannels. By using generic microfluidic setup, we assess displacement silica under controlled salt gradient and provide experimental evidence for strongly enhanced migration process, amplitude which depends on nature salt. A theoretical description shows quantitative agreement with observed features. Furthermore, describe set operations such as...

In this paper, we describe four experimental studies carried out over the last years in MMN lab, regarding dynamical behaviour of complex fluids microfluidic systems. The topics are: (1) Polymer breakup (2) Flows polymer solutions microchannels close to a smooth wall. (3) Shear banding flows (rheology, instabilities). (4) concentrated microgel particles through microchannels. Depending on situation, exploit duality low Reynolds numbers/high Weissenberg numbers (for instance, by working at...

A library of thio- and selenourea derivatives is used to adjust the kinetics PbE (E = S, Se) nanocrystal formation across a 1000-fold range (

Abstract Chiral halide perovskite nanocrystals have many applications in next‐generation optoelectronic devices due to their interaction with polarized light. Through careful selection of chiral organic surface ligands, control over the circular dichroism (CD) and circularly luminescence (CPL) these materials can be achieved. However, while recent developments CD‐active perovskites seen significant advances, effective CPL remains a challenge. Here, colloidal nanoplatelets are synthesized...

One can nowadays readily generate monodisperse colloidal nanocrystals, but the underlying mechanism of nucleation and growth is still a matter intense debate. Here, we combine X-ray pair distribution function (PDF) analysis, small-angle scattering (SAXS), nuclear magnetic resonance (NMR), transmission electron microscopy (TEM) to investigate zirconia nanocrystals from zirconium chloride isopropoxide at 340 °C, in presence surfactant (tri-n-octylphosphine oxide). Through E1 elimination,...

Fluorescent emitters like ions, dye molecules, or semiconductor nanoparticles are widely used in optoelectronic devices, usually within densely packed layers. Their luminescence properties can then be very different from when they isolated, because of short-range interparticle interactions such as Förster resonant energy transfer (FRET). Understanding these is crucial to mitigate FRET-related losses and could also lead new strategies. Exciton migration by FRET hopping between consecutive...

Modern syntheses of colloidal nanocrystals yield extraordinarily narrow size distributions that are believed to result from a rapid "burst nucleation" (La Mer, JACS, 1950, 72(11), 4847-4854) followed by diffusion limited growth and distribution focusing (Reiss, J. Chem. Phys., 1951, 19, 482). Using combination in situ X-ray scattering, optical absorption, 13C nuclear magnetic resonance (NMR) spectroscopy, we monitor the kinetics PbS solute generation, nucleation, crystal three thiourea...

Using small-angle X-ray scattering (SAXS) and interfacial tension measurements, we show that concentrated solutions of dimethyldioctylhexylethoxymalonamide diluted in dodecane are organized reverse aggregates have many features common with micelles. The critical micellar concentration is determined from measurements using the pendant-drop technique, aggregation number given by fitting SAXS data on absolute scale. effect addition n-octanol, a modifier widely used liquid/liquid extraction,...