Quantum nanostructured materials

Zhang, L.Z., Sun, W. and Cheng, P. (2003). Spectroscopic and theoretical studies of quantum and electronic confinement effects in nanostructured materials. Molecules 8, 207-222... 

The photoelectrochemical properties of different semiconductor materials have been widely reported, for single crystal, polycrystalline, as well as for nanostructured materials. In the literature various methods for measuring the efficiency are found. The most common is the JPCE (incident photon-to-current conversion efficiency) or quantum efficiency, which is defined as... 

The chapters in this volume present detailed insights into the synthesis-structure-properties relationships of nanostructured materials. In particular, the catalytic and photocatalytic properties of nanoclusters and nanostructured materials with ultrahigh surface-to-volume ratio are demonstrated. The gas absorption characteristics and surface reactivity of nanoporous and nanocrystalline materials are shown for various separation and reaction processes. In addition, the structural manipulation, quantum confinement effects, transport properties, and modeling of nanocrystals and nanowires are described. The biological functionality and bioactivity of nanostructured ceramic implants are also discussed. 

M.E. and D.P.V. acknowledge the FUNDP, the FNRS-FRFC, and the Loterie Nationale (convention n 2.4578.02) for the use of the Interuniversity Scientific Computing Facility (ISCF) centre. M.E. is particulary thankful to the Interuniversity research program (PAI/IUAP05/01) on Quantum size effects in nanostructured materials for financial support. 

Since the discovery of the intense red photoluminescence of porous silicon,much work has been devoted to this particular nanostructured material and, in the meantime, also to silicon nanoparticles. An important issue in current studies is the influence of the passivation on the photoluminescence properties. It has already been noted that, in the quantum... 

If one expected to sinq)ly extrapolate the properties of nanostructures from the size scales above or below, then there would be little reason for the current interest in nanoscience/nanotechnology. There are three reasons for nanostructured materials to behave very differently large surface/interface to volume ratios, size effects (where cooperative phenomena like ferronmgnetism is con romised by the limited number of atoms/molecules) and quantum effects. Many of the models for nmterials properties at the micron and larger sizes have characteristic length scales of nanometers (see Table II). When the size of the structure is nanometer, diose paran ters will no longer be adequate to model/predict the property. One can expect surprises - new materials behavior that may be technologically exploitable. 

He, H., Y. Zhao, B. Xu, and N. Tao. 2001. Electrochemical potential controlled electron transport in conducting polymer nanowires. Proc Electrochem Soc 19 Quantum confinement VI Nanostructured materials and devices) 20-22. 

Since the discovery of the intense red photoluminescence of porous silicon [1,2], much work has been devoted to this particular nanostructured material [4, 5] and, in the meantime, also to silicon nanoparticles [6, 7]. An important issue of current studies is the influence of the surface passivation on the photoluminescence properties. It has already been said that, in the quantum confinement model, it is essential that the surface is well passivated to avoid any dangling bonds [8]. Being middle-gap defects, these dangling bonds will quench the PL. On the other hand, the surface itself may lead to surface states that can be the origin of another kind of photoluminescence [9,10]. 

Recently, boron carbide nanostructures have attracted much attention as they have certain advantages over their bulk counterparts [147]. Nanoscale ceramic fibers, nanocylinders and nanoporous structures - as do their well-known carbon counterparts - have a tremendous number of potential applications, including uses as quantum electronic materials, structural reinforcements, and ceramic membranes for use as catalyst supports or in gas separations [148]. 

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