Nanostructures quantum behavior

Li, H. Liu, R. Liu, Y. Huang, H. Yu, H. Ming, H. Lian, S. Lee, S.-T. Kang, Z., Carbon quantum dots/Cu20 composites with protruding nanostructures and their highly efficient (near) infrared photocatalytic behavior.). Mat. Chem. 2012,22 17470-17475. 

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. 

For nanostructures, difficulties in determining the correct frequency shift arise from other factors which have an influence on the peak frequency, like strain and phonon confinement. The strain-induced shift of the optical phonon frequencies in superlattices and quantum wells can be estimated by the difference in the lattice constants of the materials. To determine the composition-dependent shift in a system with two-mode behavior, which shows strong phonon confinement, the difference in the frequency positions of the two LO-phonon modes is used, which is confinement independent in many cases [92,101,104,105]. 

Abstract Atomic undercoordination shortens and stiffens the remnant bonds to yield local quantum entrapment, densihcation, and polarization, which discriminate defects, skins, and nanostructures from the bulk, particularly in the size dependence and size-induced emergence behavior. 

Historically, nanoparticles were the first nanostructured photoelectrochemical motif to be explored and studied. A number of studies have been performed to assess the photocatalytic properties of many types of semiconductor (particularly metal oxide) nanoparticles as catalysts for oxidation reactions and purification/cleaning applications. Separately, the photoelectrode behaviors of compact, particulate semiconductor films have been analyzed. Such films serve as the backbone of the dye-sensitized photoelectrodes first popularized by O Regan and Gratzel. " Separately, semiconductor nanoparticles small enough to exhibit quantum-confinement effects have been used to prepare Schottky-type heterojunctions with the capacity for attaining values... 

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