Quantum size effects atoms relating

Quantum size effects related to the dimensionahty of a system in the nanometer range suggests a plethora of future applications using novel material properties. Whereas three-dimensional systems have an infinite extent in all three directions, in layered systems, for example atomic monolayers and thin films, the dimensionality is two, i.e. they are characterized by a limited number of layers. Consequently, a one-dimensional material is represented by wires on an atomic or molecular scale and may be realized in fibers or polymers. Zero-dimensional particles are reduced in all directions to such an extent that the properties of the original bulk system cannot... 

This chapter deals mainly with quantum size effects in CD nanocrystalline films. However, another, quite separate property of such films is related to the large percentage of atoms located on the surface of the nanocrystals of these films, e.g. —50% for a crystal size of a few nm this is the effect of adsorption of molecular and ionic species on the nanocrystal surfaces. This aspect has been dealt with much less than has size quantization therefore, it constitutes only a very small part of this chapter, mainly Section 10.2.3, which discusses the effect of adsorbed water on CD CdSe films. Section 9.2.2.2 deals in somewhat more detail with this particular issue. 

Recently, Pcs organized on surface have been used as molecular probes for the determination of quantum confined effects [207], CoPc molecules form ordered self-assembled monolayers (SAM) on the top of Pb(lll) thin films grown on a Si( 111) substrate with the Pc units lying flat on the surface, as revealed by atomically resolved STM. A close analysis of the STM data revealed that the Pc molecules adsorb and self-assemble on the surface following a thickness-dependent adsorption pattern, which is ultimately related to the quantum size effects of the metal surface. 

It is important that much the data relate to the case when the active component particles cannot be treated as clusters of atoms and that need strict consideration of the quantum size effects, but as a continuous phase with the properties described by standard methods of the continuous phase thermodynamics. Inspection of these experimental data reveals that... 

The size-evolution of the physical properties from atom to bulk might also be related in part to the variation of the surface-to-volume ratio. In addition to these classical effects, however, the quantum mechanical properties of the electrons play an equally important role. These so-called quantum-size effects can be understood most simply by realizing that a conduction electron in a metal has both particle-and wave-like properties, according to the famous particle-wave duality of quantum mechanics. Treated as a wave-phenomenon, the electron in a metal has a wavelength of one to a few nanometers. The wave-character of the electron will... 

Nanoparticles have few atoms that suffice only to form an identifiable (crystal) interior and the interactions among these atoms in a small limited size bring the properties close to the discrete conditions displayed by isolated molecules or atomic pairs. These phenomena are commonly related to quantum size effects, and are revealed mainly in optical and electrical properties. 

Electronic charge densities have fundamental influence on a wide variety of molecular properties. Electron densities are related to the formal sizes of atoms and the formal bond lengths of molecules, for example, in various crystals [278], and there are important relations between experimental electron densities and temperature [279]. Electronic charge densities p(r) can be calculated by various quantum chemical methods, both ab initio and semiempirical (see, e.g., refs. [90,91]). Density difference calculations are used for direct comparisons of electronic structures (see, e.g., ref. [280]), whereas the effects of electron correlation on charge densities are of special importance in the study of nonbonded interactions [281]. 

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