Controlling the electronic structure of nanocrystal assemblies by variation of the particle-particle interaction
ABSTRACT The change in the electronic structure of germanium nanocrystals is investigated as their concentration is increased from noninteracting, individual particles to assembled arrays of particles. The electronic structure of the individual nanoclusters shows clear effects due to quantum confinement which are lost in the concentrated assemblies of bare particles. When the surface of the individual particles is passivated, they retain their quantum confinement properties also upon assembly. These effects are interpreted in terms of a particle-particle interaction model. (C) 2004 American Institute of Physics.
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ABSTRACT: Since ZnSe is less toxic than cadmium based materials, ZnSe nanocrystal is a potential candidate for optoelectronic and fluorescent labelling applications. In this paper, colloidal ZnSe nanocrystals are successfully synthesized from zinc stearate and elemental selenium in a paraffin hot-matrix. The method is environment-friendly and of low cost compared with the conventional methods, which are generally toxic and expensive. The nanocrystal–nanocrystal interactions will significantly affect the optical properties and thus a detailed study is desirable. Here, we comprehensively study the interaction through the van der Waals interaction energy, electrostatic energy, steric energy and depletion interaction energy. The corresponding photoluminescence and absorption spectra show obvious excitonic features. Our results show that the nanocrystals can be converted to a water-dispersible system when the dominant emission is still from the excitonic recombination on ZnSe nanocrystals.Journal of Physics D Applied Physics 06/2009; 42(12):125410. DOI:10.1088/0022-3727/42/12/125410 · 2.52 Impact Factor
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ABSTRACT: We report intrinsic photoluminescence in the ultraviolet for adamantane (C10H16), the smallest in a series of hydrogen-passivated diamond clusters (diamondoids). The luminescence is ascribed to recombination of self-trapped excitons. The inclusion of high amounts of nitrogen into the nanodiamond’s crystal lattice, using the example of urotropine (hexamethylenetetramine), is found to quench the luminescence. The results show that diamondoids are promising semiconductor nanocrystals for nanophotonic applications in the ultraviolet spectral region.Physical Review B 11/2009; 80(20). DOI:10.1103/PhysRevB.80.205323 · 3.66 Impact Factor
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ABSTRACT: In this article, we show how to produce materials consisting of regularly ordered Ge quantum dot lattices in an amorphous alumina matrix with a controllable Ge quantum dot size, shape, spacing, crystalline structure, and degree of regularity in their ordering. The production of such materials is achievable already at room temperature by magnetron sputtering deposition of a (Ge + Al2O3)/Al2O3 multilayer. The materials show photoluminescence in the visible and ultraviolet light range, a size-dependent blue shift of the photoluminescence peak and an enhancement of its intensity by size reduction, indicating the quantum dot origin of the photoluminescence. The materials also exhibit excellent mechanical properties due to the alumina matrix. Their internal structure is shown to be highly resistive to irradiation with energetic particles for a large range of the irradiation parameters.Journal of Nanoparticle Research 03/2013; 15(3). DOI:10.1007/s11051-013-1485-9 · 2.28 Impact Factor