Fluorescence Retrieval of CdSe Quantum Dots by Self-Assembly of Supramolecular Aggregates of Reverse Micelles

Life is restored to inactive (dead) quantum dots by means of the encapsulation into supramolecular aggregates of spherical nonionic Igepal micelles.

Ordered and twinned structure in hexagonal-based potassium tungsten bronze nanosheets

Non-stoichiometric hexagonal-based potassium tungsten bronze (KxWO3) nanosheets were synthesized by oxidizing tungsten foil in potassium hydroxide. The tungsten bronze nanosheets exhibited an ordered monoclinic superstructure as revealed by X-ray diffraction patterns. Further detailed structural investigation by employing electron microscopy techniques showed the coexistence of 120° rotation twinning variants in the superstructure phase, which may result from the rotation symmetry reduction induced by the ordered arrangements of K vacancies during crystal growth.

Controlled synthesis of compositionally tunable ternary PbSe(x)S(1-x) as well as binary PbSe and PbS nanowires

High-quality compositionally tunable ternary PbSe(x)S(1-x) (x = 0.23, 0.39, 0.49, 0.68, and 0.90) nanowires (NWs) and their binary analogues have been grown using solution-liquid-solid growth with lead(II) diethyldithiocarbamate, Pb(S(2)CNEt(2))(2), and lead(II) imido(bis(selenodiisopropylphosphinate)), Pb((SeP(i)Pr(2))(2)N)(2), as single-source precursors. The alloyed nature of PbSe(x)S(1-x) wires was confirmed using ensemble X-ray diffraction and energy dispersive X-ray spectroscopy (EDXS). Single NW EDXS line scans taken along the length of individual wires show no compositional gradients. NW compositions were independently confirmed using inductively coupled plasma atomic emission spectroscopy. Slight stoichiometric deviations occur but never exceed 13.3% of the expected composition, based on the amount of introduced precursor. In all cases, resulting nanowires have been characterized using transmission electron microscopy. Mean diameters are between 9 and 15 nm with accompanying lengths that range from 4 to 10 μm. Associated selected area electron diffraction patterns indicate that the PbSe(x)S(1-x), PbSe, and PbS NWs all possess the same <002> growth direction, with diffraction patterns consistent with an underlying rock salt crystal structure.