Hollow nanocrystals can be synthesized through a mechanism analogous to the Kirkendall Effect, in which pores form because of difference diffusion rates between two components couple. Starting with cobalt nanocrystals, we show that their reaction solution oxygen and either sulfur or selenium leads formation hollow resulting oxide chalcogenides. This process provides general route synthesis nanostructures large number compounds. A simple extension yielded platinum-cobalt yolk-shell...

Cation exchange has been investigated in a wide range of nanocrystals varying composition, size, and shape. Complete fully reversible occurs, the rates reactions are much faster than bulk cation processes. A critical size identified below which shapes complex evolve toward equilibrium shape with lowest energy during reaction. Above anion sublattice remains intact basic initial retained throughout exchange. The size-dependent change can also be used to infer features microscopic mechanism.

The partial transformation of ionic nanocrystals through cation exchange has been used to synthesize nanocrystal heterostructures. We demonstrate that the selectivity for take place at different facets plays an important role in determining resulting morphology binary heterostructure. In case copper(I) (Cu(+)) cadmium sulfide (CdS) nanorods, reaction starts preferentially ends nanorods such copper (Cu(2)S) grows inward from either end. is very striped pattern obtained our previous studies...

Abstract Formation of cobalt sulfide hollow nanocrystals through a mechanism similar to the Kirkendall Effect has been investigated in detail. It is found that performing reaction at > 120 °C leads fast formation single void inside each shell, whereas room temperature multiple voids are formed within which can be attributed strongly temperature‐dependent diffusivities for vacancies. The process dominated by outward diffusion cations; still, occurrence significant inward transport sulfur...

In the present work, we analyze geometry and composition of nanostructures obtained from oxidation iron nanoparticles. The initial takes place by outward diffusion cations through growing oxide shell. This net material flow is balanced an opposite vacancies, which coalesce at metal/oxide interface. Thus, partial colloidal nanoparticles leads to formation core−void−shell nanostructures. Furthermore, complete in 3−8 nm size range hollow We temperature vacancy coalescence during...

Pt nanoparticles are deposited photochemically on the surfaces of colloidal CdS nanorods and CdSe/CdS nanoheterostructures. While deposits at varying positions along nanorods, deposition occurs preferentially near CdSe core.

Branched nanocrystal heterostructures synthesized from CdSe and CdTe exhibit a type II band structure alignment that induces separation of charge upon photoexcitation localizes carriers to different regions the tetrahedral geometry. The dynamics carrier relaxation examined with femtosecond pump−probe spectroscopy showed having rise times biexponential decays longer than those nanorods similar dimensions. This is attributed weaker interactions surface states nonradiative channels afforded by...

Microporous manganese oxides have been prepared by nonaqueous sol−gel reactions involving tetrabutylammonium (TBA) or tetraethylammonium (TEA) permanganate and methanol in the presence of alkali cation dopants. Layered birnessite-type materials were obtained for Na+ K+ dopants a 0.5:1 reactant ratio with manganese. Na−birnessite was isolated hydrated dehydrated forms (7 vs 5.6 Å interlayer spacing) whereas only K−birnessite observed. Cryptomelane generated K:Mn 0.25:1. Spinel formed Li+...

Nanocrystals of cadmium selenide exhibit a form polytypism with stable forms in both the wurtzite and zinc blende crystal structures. As result, nanorods tend to stacking faults along c-axis. These were found preferentially during growth (001) face, which accounts for 40% rod's total length. Since II-VI semiconductor lack inversion symmetry c-axis particle, two ends nanorod may be identified by this anisotropic distribution faults.

This communication reports the development of a TiO2–streptavidin nanoconjugate as new biological label for X-ray bio-imaging applications; this probe, used in conjunction with nanogold will make it possible to obtain quantitative, high-resolution information about location proteins using microscopy.

We report on high-resolution transmission electron microscope structural studies of InAs colloidal semiconductor nanocrystal quantum dots (NCQDs) ultrathin GaAs (001) single-crystal substrates. employ a benign method for preparing transparent specimens that is suitable the study such fragile samples. The image contrast comprises contributions from scattering both NCs and substrate. Long-term exposure reveal different damage mechanisms operative in nanocrystals

Integration of semiconductor epitaxical nanostructures and nanocrystals into two classes quantum structures, uncovered adsorbed or buried via overgrowth, is successfully demonstrated through structural optical studies. The combination InGaAs/GaAs structures InAs employed as a vehicle with the functional aim exploiting well developed optoelectronic communication technology based on former biochemical biomedical applications for which latter are suited.

Silver gallium sulfide nanocrystals were synthesized and characterized by fluorescence, TEM, EDS, XRD to better understand the material system with an ideal band gap of 2.7 eV. The crystals found nucleate in monoclinic structure, develop two fluorescence peaks (650, 460 nm) influenced stoichiometry.

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ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTStereochemistry of the Thermal Retro-Diels−Alder Reactions cis,exo-5,6-d2-Bicyclo[2.2.1]hept-2-ene, cis-4,5-d2-Cyclohexene, and cis,exo-5,6-d2-Bicyclo[2.2.2]oct-2-eneDavid K. Lewis, David A. Glenar, Steven Hughes, Bansi L. Kalra, Jessica Schlier, Rajesh Shukla, John E. BaldwinView Author Information Department Chemistry, Connecticut College New London, 06320 Syracuse University Syracuse, York 13244 Cite this: J. Am. Chem. Soc. 2001, 123, 5,...

ADVERTISEMENT RETURN TO ISSUEPREVAddition & Corre...Addition CorrectionORIGINAL ARTICLEThis notice is a correctionFemtosecond Spectroscopy of Carrier Relaxation Dynamics in Type II CdSe/CdTe Tetrapod HeteronanostructuresP. Peng, D. J. Milliron, S. M. Hughes, Justin C. Johnson, A. Paul Alivisatos, and Richard SaykallyCite this: Nano Lett. 2005, 5, 12, 2651Publication Date (Web):December 14, 2005Publication History Published online14 December 2005Published inissue 1...

A modulation-demodulation scheme substantially enhances diffusion-dominated-adaptive-interferometric sensitivity. The path length sensitivity is improved by converting a quadratic small-signal response, easily drowned in system noise, to linear response mixing with strong phase modulation. This conversion also shifts low-frequency signals away from 1/f noise. Experimental results show 180 fm/ [square root]Hz displacement for 5 Hz signal few milliwatts of optical power, an improvement 3...

The number of renewable sources, namely photovoltaics (PV), continues to grow within distribution systems. How placements impact a system's performance remains concern both the research and utility communities. Beyond system node voltages real power losses, this work looks industry standard imbalance metrics changes experienced on these values with varied levels PV. Specifically, four are presented studied for an actual 906-bus system. Multiple loading conditions photovoltaic placement...