Christopher B. Murray

Bio: Christopher B. Murray is an academic researcher from University of Pennsylvania. The author has contributed to research in topics: Nanocrystal & Quantum dot. The author has an hindex of 88, co-authored 336 publications receiving 54410 citations. Previous affiliations of Christopher B. Murray include Universal Display Corporation & Lawrence Berkeley National Laboratory.

Systematic electron crystallographic studies of self-assembled binary nanocrystal superlattices.

Abstract: Multicomponent nanocrystal assemblies have received great attention due to their fundamental role in the study of self-assembly and novel physical properties arising from particle interactions. Here, we report the formation of the first binary nanocrystal superlattices (BNSLs) consisting of different-sized Fe3O4 nanocrystals. We establish a framework to systematically study the structure of BNSLs using a dual-axis tomography TEM holder. The tilt series obtained not only allows us to map the three-dimensional (3D) structure of icosahdedral AB13 (ico-AB13) and AlB2-type BNSLs but also uncovers the structural differences among the projections of ico-AB13, cuboctahedral AB13 (cub-AB13), and AlB2. This structural characterization method is general and is important for further exploration of structural diversity in BNSLs and in the development of rigorous structure−property relationships in BNSLs. The formation of ico-AB13 and AlB2 BNSLs from electrostatically neutral Fe3O4 nanoparticles is consistent with the ...

In situ repair of high-performance, flexible nanocrystal electronics for large-area fabrication and operation in air.

Abstract: Colloidal semiconductor nanocrystal (NC) thin films have been integrated in light-emitting diodes, solar cells, field-effect transistors (FETs), and flexible, electronic circuits. However, NC devices are typically fabricated and operated in an inert environment since the reactive surface and high surface-to-volume ratio of NC materials render them sensitive to oxygen, water, and many solvents. This sensitivity has limited device scaling and large-scale device integration achievable by conventional fabrication technologies, which generally require ambient air and wet-chemical processing. Here, we present a simple, effective route to reverse the detrimental effects of chemical and environmental exposure, by incorporating, in situ, a chemical agent, namely, indium metal, which is thermally triggered to diffuse and repair the damage. Taking advantage of the recovery process, CdSe NC FETs are processed in air, patterned using the solvents of lithography, and packaged by atomic layer deposition to form large-ar...

Dendron-Mediated Engineering of Interparticle Separation and Self-Assembly in Dendronized Gold Nanoparticles Superlattices

Abstract: Self-assembly of nanoparticles into designed structures with controlled interparticle separations is of crucial importance for the engineering of new materials with tunable functions and for the subsequent bottom-up fabrication of functional devices. In this study, a series of lipophilic, highly flexible, disulfide dendritic wedges (generations 0–4), based on 2,2-bis(hydroxymethyl)propionic acid, was designed to bind Au nanoparticles with a thiolate bond. By controlling the solvent evaporation rate, the corresponding dendron-capped Au hybrids were found to self-organize into hexagonal close-packed (hcp) superlattices. The interparticular spacing was progressively varied from 2.2 to 6.3 nm with increasing dendritic generation, covering a range that is intermediate between commercial ligands and DNA-based ligand shells. Dual mixtures made from some of these dendronized hybrids (i.e., same inner core size but different dendritic covering) yielded binary superlattice structures of unprecedented single inorgan...

Ultrafast electron trapping at the surface of semiconductor nanocrystals: excitonic and biexcitonic processes.

Abstract: Aging of semiconductor nanocrystals (NCs) is well-known to attenuate the spontaneous photoluminescence from the band edge excitonic state by introduction of nonradiative trap states formed at the NC surface. In order to explore charge carrier dynamics dictated by the surface of the NC, femtosecond pump/probe spectroscopic experiments are performed on freshly synthesized and aged CdTe NCs. These experiments reveal fast electron trapping for aged CdTe NCs from the single excitonic state (X). Pump fluence dependence with excitonic state-resolved optical pumping enables directly populating the biexcitonic state (XX), which produces further accelerated electron trapping rates. This increase in electron trapping rate triggers coherent acoustic phonons by virtue of the ultrafast impulsive time scale of the surface trapping process. The observed trapping rates are discussed in terms of electron transfer theory.

The H2 Pressure Dependence of Hydrodeoxygenation Selectivities for Furfural Over Pt/C Catalysts

Abstract: Hydrodeoxygenation of furfural was studied over a 10-wt% Pt/C catalyst at 453 K, under both low- and high-pressure conditions. With vapor-phase furfural as the feed and H2 pressures below 1 bar, decarbonylation to furan is a major product, with the selectivity to furfuryl alcohol and dimethylfuran increasing with increasing H2 pressure. When the reaction is performed at 33 bar, using 1-wt % furfural in 1-propanol solvent and high-pressure H2, no evidence for decarbonylation was observed. At high pressures, the reaction is sequential, with all the furfural proceeding to methylfuran, which in turn reacts to over-hydrogenated products, including 2-methyltetrahydrofuran and 2-pentanone. It is suggested that the hydrogen surface coverage is responsible for the apparent differences in the reaction network at high and low pressures.

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Semiconductor Clusters, Nanocrystals, and Quantum Dots

Abstract: Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Abstract: Highly luminescent semiconductor quantum dots (zinc sulfide-capped cadmium selenide) have been covalently coupled to biomolecules for use in ultrasensitive biological detection. In comparison with organic dyes such as rhodamine, this class of luminescent labels is 20 times as bright, 100 times as stable against photobleaching, and one-third as wide in spectral linewidth. These nanometer-sized conjugates are water-soluble and biocompatible. Quantum dots that were labeled with the protein transferrin underwent receptor-mediated endocytosis in cultured HeLa cells, and those dots that were labeled with immunomolecules recognized specific antibodies or antigens.