Electron-hole attraction

Electron-electron repulsion implies electron-hole attraction. If the crystal symmetry is such that a band gap occurs, one expects this attraction to lead to the formation of excitons. 

The l Bj state is now an exciton-polaron. Its structure is qualitatively similar in both the noninteracting and interacting limits, as the soliton-antisoliton confinement due to linear confinement arising from the effective extrinsic bond alternation has a rather similar effect to electron-hole attraction. However, as already predicted, the state has a more pronounced distortion because it... 

Leitsmann, R., Schmidt, W. G., Hahn, P. H., Bechstedt, F. (2005). Second-harmonic polarizability including electron-hole attraction from band-structure theory. Physical Review B - Condensed Matter and Materials Physics, 72(19), 195209/1-195209/10. 

According to a large number of experimental studies, the most stable phologen-erated species in the lowest excited stales of conjugated chains are electron-hole pairs bound by Coulomb attraction and associated to a local deformation of the backbone, i.e., polaron-excilons [18]. A good insight into the properties of these species can be provided by quantum-chemical calculations our recent theoretical... 

If for example Ti02, is used to capture sunlight in a photo-catalytic reaction then only about 10% of the available spectrum will be of use, since it requires 3.2 eV to create an electron-hole pair in Ti02. Both the photovoltaic and the photochemical methods are of potential interest, but at present they are too expensive. Also, the production of semiconductors used in photovoltaic cells consumes much energy. Nevertheless, the prospect remains attractive. If cells could be made with an efficiency of say 10 % then only 0.1 % of the earths surface would be required to supply our present energy consumption ... 

C and C are the electrostatic attractive interactions of the excess electron of one fragment with the electron hole of the other fragment and G and G are local fragment excitation energies. 

Theoretical investigations of AEV and AEC have indicated that the ratio AEV/AEC is greater than 1 [Zh2, Vo2, Ne2] and may be as high as 3 for the case of hydrogenated silicon clusters [Re3], In a similar calculation for thin silicon films, even-odd oscillations of A v according to the number of Si monolayers have been found [Zh2], For the latter case the ratio AEy/AEc showed values between 1 and 2. The results of a study [Wa5] including the decrease in the static dielectric constant with size are close to the experimentally [Bu2] observed values of about 2 for the ratio AEy/AEc, as shown in Fig. 7.16. In this work [Wa5], it is concluded that the electron-hole pair is confined by the physical dimension of the quantum dot, not by Coulomb attraction. 

The study of atoms and molecules in external fields is a fascinating area of research that has attracted much attention from different areas of science and engineering. Following the influential work of Loudon in 1959, in which he performed the quantum mechanical analysis of the behavior of a one-dimensional hydrogen atom in various Coulomb potentials [1], many studies have been carried out to understand the physics of excitons (hydrogen-like electron-hole pair) and some related systems [2-5]. The discovery of neutron stars and white dwarf stars further motivated rapid development of this field since it stimulated the interest of studying the variation of electronic structure and behavior of atomic and... 

That products of intermediate oxidation level can be detected in the photocatalytic reactions of hydrocarbons and fossil fuels is also consistent with a surface bound radical intermediate . Photocatalytic isotope exchange between cyclopentane and deuterium on bifunctional platinum/titanium dioxide catalysts indicates the importance of weakly adsorbed pentane at oxide sites. The platinum serves to attract free electrons, decreasing the efficiency of electron-hole recombination, and to regenerate the surface oxide after exchange. Much better control of the exchange is afforded with photoelectrochemical than thermal catalysis > ) As before, hydrocarbon oxidations can also be conducted at the gas-solid interface... 

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