Local trap

Fig. 3.7. Trap-controlled carrier recombination 1 - excitation of solid with creation of electron ( ) and hole (0) pair 2, 3 - their localization (trapping) by defects 4 - thermal ionization of electron from a trap 5 - its recombination with the recombination centre.

Similar conclusions on the character of conductance in the polycrystalline diamond films were derived in [33], The resistive intercrystallite boundaries can involve nonlinear resistance in polycrystalline diamond films moderately doped with boron [34]. Later, more sophisticated analysis [35-37] of the frequency dependence of impedance of polycrystalline diamond films resulted in a conclusion that at higher temperatures, in addition to the aforementioned electric conductance caused by the motion of free holes in the valence band, a second component of conductance manifests itself. The second component is due to the hopping of charge carriers between local traps possibly associated with the intercrystallite boundaries. 

In most organic semiconductors the presence of charges modifies the local structure of the network by deformation of the particular site. This so-called polaron formation thus creates scattering centres for other charges. Moreover these locally trapped carriers commonly alter the energy conditions because of their Coulomb interaction. In combination with the polaron energy, the latter may be attractive or repulsive. These effects, as they involve more than one electron, force us to give up the one-electron picture and hence to use the correlated-electron description. 

If local traps are distributed in energy (E), they will be filled from bottom to top as electric fields, F, increase. The quasi-Fermi level will scan the distribution shifting towards the transport band, and 0 = rif/rit will become a function of F. A general form of nt = nt(iif) relation can be obtained from a detailed balance equation as [363]... 

A simplified view of the early processes in electron solvation is given in Fig. 9 (i) the electron is ejected from a molecule upon ionization by radiolysis or photolysis (ii) in the thermalization step, the ejected electron progressively loses its excess kinetic energy in collisions with solvent molecules (iii) then, the electron is localized, trapped in a solvent site or cavity and (iv) becomes solvated when the solvent molecules have obtained their equilibrium configuration after relaxation. 

The delineation of local traps was facilitated by combining the stripped-off paleo-geological map with the map of the present structure. In this way we were able to exclude certain disturbed portions of wedge zones where the traps have been destroyed by later tectonic movements. 

We will treat color separately for the different minerals and just add a few notes here the importance of dopants is clear from Table 36.5. There are several different causes of color in gemstones. Most are associated with local trapped charges. 

Class / Localized (trapped) valences. For example, in proteins there are often iron or copper ions in different valence states. The same is the case with sparse impurity ions in solids. The spectra are sum spectra for the different valences. 

It is well understood that the carbon structure of films is transformed by irradiation. A gap is observed in the electronic structure of carbon that changes the electrical properties of the material from conducting to insulating. Moreover, localized traps are observed in the pseudogap region of the irradiated sample, which... 

In order to be trapped by a structural defect, the positron must first diffuse to the defect and then make the transition from the free Bloch state to the localized trapped state. One... 

Cold, trapped HD+-ions are ideal objects for direct spectroscopic tests of quantum-electrodynamics, relativistic corrections in molecules, or for determining fundamental constants such as the electron-proton mass ratio. It is also of interest for many applications since it has a dipole moment. The potential of localizing trapped ions in Coulomb crystals has been demonstrated recently with spectroscopic studies on HD+ ions with sub-MHz accuracy. The experiment has been performed with 150 HD+ ions which have been stored in a linear rf quadrupole trap and sympathetically cooled by 2000 laser-cooled Be+ ions. IR excitation of several rovibrational infrared transitions has been detected via selective photodissociation of the vibra-tionally excited ions. The resonant absorption of a 1.4/itm photon induces an overtone transition into the vibrational state v = A. The population of the V = A state so formed is probed via dissociation of the ion with a 266 nm photon leading to a loss of the ions from the trap. Due to different Franck-Condon factors, the absorption of the UV photon from the v = A level is orders of magnitude larger than that from v = 0. 

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