Publications

2009
Hadar Steinberg, Yigal Lilach, Asaf Salant, Omri Wolf, Adam Faust, Oded Millo, and Uri Banin. 2009. “Anomalous temperature dependent transport through single colloidal nanorods strongly coupled to metallic leads.” Nano letters, 9, 11, Pp. 3671-3675. Publisher's Version Abstract

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We report wiring of individual colloidal nanorods (NRs), 30−60 nm long by 3.5−5 nm diameter. Strong electrical coupling is achieved by electron beam induced deposition (EBID) of metallic lines targeting NR tips with nanometric precision. At T = 4 K many devices exhibit smooth I(V) curves with no sharp onset features, which remarkably fit a Fowler−Nordheim tunneling model. All devices exhibit an anomalous exponential temperature dependence of the form I ∼ exp(T/T0). This irregular behavior cannot be explained by any hopping or activation model and is interpreted by accounting for the lowering of the NR conduction band due to lattice dilation and phonon coupling.

Gabi Menagen, Janet E Macdonald, Yossi Shemesh, Inna Popov, and Uri Banin. 2009. “Au growth on semiconductor nanorods: photoinduced versus thermal growth mechanisms.” Journal of the American Chemical Society, 131, 47, Pp. 17406-17411. Publisher's Version Abstract

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Gold growth on CdS nanorods and on seeded CdSe/CdS nanorods with and without illumination at different temperatures was studied. Two competing mechanisms were identified: thermal and light-induced growth. The thermal mechanism leads to growth of small gold particles at defects along the rod body and can be suppressed at lower temperatures. This control is attributed to a phase transition of the alkyl chains of the surface amine ligands to a static phase at lower temperatures, blocking the Au precursor’s access to the nanorod surfaces. While a long-chain (C18) amine shows effective blocking at 293 K, a shorter chain (C12) amine shows the same result only at 273 K; however, in the case of a bulky trialkylamine, defect growth was observed even at 273 K. Light-induced growth leads to selective deposition of gold on one end of the rods. The tip was shown to grow on sulfur-rich facets of the nanorod, producing end-on and angled tip orientations. Growth under illumination with decreased temperature provides a highly selective synthesis of hybrid semiconductor nanorods with a single gold tip. Such anisotropic semiconductor−metal hybrids are of interest for self-assembly and photocatalysis and as building blocks in optoelectronic devices.

Miri Kazes, Tsiala Saraidarov, Renata Reisfeld, and Uri Banin. 2009. “Organic–inorganic sol–gel composites incorporating semiconductor nanocrystals for optical gain applications.” Advanced Materials, 21, 17, Pp. 1716-1720. Publisher's Version Abstract

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Organic‐inorganic sol‐gel composite incorporating highly emitting CdSe/ZnS quantum dots and CdSe/CdS/ZnS quantum rods is reported. Optical gain measurements conducted on a quantum rod/sol‐gel composite film show stable room temperature amplified spontaneous emission under ambient conditions.

Ehud Shaviv, Asaf Salant, and Uri Banin. 2009. “Size dependence of molar absorption coefficients of CdSe semiconductor quantum rods.” ChemPhysChem, 10, 7, Pp. 1028-1031. Publisher's Version Abstract

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Fundamental properties: The molar absorption coefficients of CdSe quantum rods are determined experimentally as a function of their dimensions (see figure). Far above the band gap a simple dependence on volume is seen. The behavior at the band gap manifests a concentration of oscillator strength with decreased diameter in agreement with strong quantum confinement behavior.

Meike L Schipper, Gopal Iyer, Ai Leen Koh, Zhen Cheng, Yuval Ebenstein, Assaf Aharoni, Shay Keren, Laurent A Bentolila, Jianquing Li, and Jianghong Rao. 2009. “Particle size, surface coating, and PEGylation influence the biodistribution of quantum dots in living mice.” Small, 5, 1, Pp. 126-134. Publisher's Version Abstract

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This study evaluates the influence of particle size, PEGylation, and surface coating on the quantitative biodistribution of near-infrared-emitting quantum dots (QDs) in mice. Polymer- or peptide-coated 64Cu-labeled QDs 2 or 12 nm in diameter, with or without polyethylene glycol (PEG) of molecular weight 2000, are studied by serial micropositron emission tomography imaging and region-of-interest analysis, as well as transmission electron microscopy and inductively coupled plasma mass spectrometry. PEGylation and peptide coating slow QD uptake into the organs of the reticuloendothelial system (RES), liver and spleen, by a factor of 6-9 and 2-3, respectively. Small particles are in part renally excreted. Peptide-coated particles are cleared from liver faster than physical decay alone would suggest. Renal excretion of small QDs and slowing of RES clearance by PEGylation or peptide surface coating are encouraging steps toward the use of modified QDs for imaging living subjects.

Uri Banin, David Avnir, Taleb Mokari, and Hanan Sertchook. 2009. “Spherical composites entrapping nanoparticles, processes of preparing same and uses thereof.” United States of America. Publisher's Version Abstract
Novel nanoparticles-entrapping spherical composites, composed of a metal oxide or semi-metal oxide and a hydrophobic polymer, are disclosed. The spherical composites are characterized by well-defined spherical shape, a narrow size distribution and high compatibility with various types of nanoparticles. Further disclosed are processes for preparing the nanoparticles-entrapping spherical composites and uses thereof.