Charge transfer in solids

The special interest of pure quadrupole resonance is that it affords a means of measuring the small charge transfer in solid complexes. 

Basic Relationships Between the Defect Equilibria and Charge Transfer in Solids 59... 

The junction between an electronic conductor and a polymeric proton conductor gives a very interesting tool for the study of mass and charge transfer in solids and in solutions. In addition, the perfluorosulphonic proton conductor gives new synthesis routes in organic or electro-organic chemistry. Future developments in this family of proton conductors are to be expected for the preparation of low price perfluorinated materials. 

Z. G. Soos and D. J. Klein, Charge-transfer in solid-state complexes, in Molecular Association, Vol. 1 59. 

Figure 8.15 Calculated composition versus oxygen stoichiometry curves for Lai- SrjCoCb-s. [The two experimental points are taken from data in A. N. Petrov, V. A. Cherepanov, and A. Y. Zuev, Thermodynamics, Defect Structure and Charge Transfer in Doped Lanthanum Cobaltites An Overview, J. Solid State Electrochem., 10, 517-537 (2006).]...

So far we have outlined the conceptual framework in which we discuss charge transfer in organic semiconductors. It is based on a molecular picture where the molecular unit is considered central, with interactions between molecular units added afterwards. For amorphous molecular solids and for molecular crystals this approach is undisputed. In the case of semiconducting polymers, a conceptually different view has been proposed that starts from a one-dimensional (ID) semiconductor band picture, and that is generally known as the Su-Schrieffer-Heeger (SSH) model [21-24]. 

Fig. 3 Charge transfer in DNA hairpins after photoexcitation of stilbene linker (St) by a laser pulse [45]. A hole, first, undergoes a transition from photoexcited St to the adjacent GC pair as shown by the solid arrow. Then it can either hop to next GC pairs (dot-dashed arrow) or return to St with the subsequent electron-hole recombination (dotted arrow)...

The highest ratio is obtained in the 2,7-dinitro derivative. It is probable that the planarity of the nitro derivatives and the way the molecules are packed in the bulk play an important role in the photoelectric behavior. A self-complex type of structure may be formed, which favors charge transfer in the solid. 

At the early stages the photoconductivity of solid solutions of the leucobase of malachite green in various organic media was investigated [285]. In these systems, carrier transport occurs by direct interaction between the leucobase molecules. No direct participation of the organic matrix in the charge transfer was observed. A model was proposed which links charge transfer in these systems with impurity conduction in semiconductors. 

The analysis conducted in this Chapter dealing with different theoretical approaches to the kinetics of accumulation of the Frenkel defects in irradiated solids (the bimolecular A + B —> 0 reaction with a permanent particle source) with account taken of many-particle effects has shown that all the theories confirm the effect of low-temperature radiation-stimulated aggregation of similar neutral defects and its substantial influence on the spatial distribution of defects and their concentration at saturation in the region of large radiation doses. The aggregation effect must be taken into account in a quantitative analysis of the experimental curves of the low-temperature kinetics of accumulation of the Frenkel defects in crystals of the most varied nature - from metals to wide-gap insulators it is universal, and does not depend on the micro-mechanism of recombination of dissimilar defects - whether by annihilation of atom-vacancy pairs (in metals) or tunnelling recombination (charge transfer) in insulators. 

Charge transfer in matter arises from the ability of the charge carriers to migrate under the influence of an applied potential field. In general, solids fall into three groups as far as their conducting properties are concerned (Fig. 1). 

Projection of the [TCNQ-TTF] crystal structure onto the b-c plane solid and dotted lines indicate the helical paths of pairwise charge transfer in the <010> direction. The TTF (open circles) are behind the TCNQ (solid circles). 

Charge transfer occurs when particles collide with each other or with a solid wall. For monodispersed dilute suspensions of gas-solid flows, Cheng and Soo (1970) presented a simple model for the charge transfer in a single scattering collision between two elastic particles. They developed an electrostatic theory based on this mechanism, to illustrate the interrelationship between the charging current on a ball probe and the particle mass flux in a dilute gas-solid suspension. This electrostatic ball probe theory was modified to account for the multiple scattering effect in a dense particle suspension [Zhu and Soo, 1992]. 

Electrochemistry, to distinguish it from the topics discussed in previous sections, is concerned with low-energy charge transfer in solution. The electron transfer typically occurs on the surface of a charged (usually metal) electrode. Possible chemical reactions that may occur, and that may be of importance in chemical synthesis, are the generation or annihilation of gases (in an electrolysis or a fuel cell, respectively) and the generation or neutralization of ions, which may be accompanied with the dissolution or deposition of a solid material. 

St. Jean, M., H. N. Hau, C. Rigaux, and G. Furdin. 1983. Optical determination of the charge transfer in AsF5-graphite intercalation compounds. Solid State Commun. 46 55-58. 

Fig. 1.34. Excited state energy levels. The singlet (Si) energy levels of OPVn and MP-C60 (solid bars) were determined from fluorescence data. The MP-C6o(Ti) level (solid bar and dashed line) was taken from phosphorescence data in the literature [107]. The levels of the charge-separated states for (a) intermolecular charge transfer in OPVra/M P-CV,o mixtures and (b) intramolecular charge transfer in OPVn-Cgo dyads were determined using (1.2) (see text and Table 1.3). Open squares are for toluene and solid squares for ODCB...

The direct connection between nuclear quadrupole coupling constant and charge distribution leads to the expectation that NQR should be a sensitive device for the study of intermolecular charge transfer in the solid state. The nu-... 

High-speed linear-sweep voltammetry (LSV) or linear potential sweep chronoamperometry (top) potential waveform (bottom) current response. The areas between the solid lines and the dotted lines measure approximately the charge transferred in the oxidation or reduction. 

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