Charge motion

Molecular transport junctions differ from traditional chemical kinetics in that they are fundamentally electronic rather than nuclear - in chemical kinetics one talks about nucleophilic substitution reactions, isomerization processes, catalytic insertions, crystal forming, lattice changes - nearly always these are describing nuclear motion (although the electronic behavior underlies it). In general the areas of both electron transfer and electron transport focus directly on the charge motion arising from electrons, and are therefore intrinsically quantum mechanical. 

Recent theoretical investigations suggest that the discrepancy between theoretical and experimental values of the hopping rate is due to the underestimation of localization phenomena in the description of charge motion behavior. These phenomena can result from the coupling of electronic motion to vibrational dynamics of base pairs [47] and can also be caused by polarization of the molecule or solvent [34, 48]. In the latter case theoretically possible effects include ... 

P.W. Cleary, Predicting charge motion, power draw, segregation and wear in ball mills using discrete element methods, Miner. Eng. 11 (1998) 1061-1080. 

From a chemical perspective, the double-helix produced by two intertwining strands of oligomeric DNA is a fascinating and unique molecular structure. (See Fig. 1 for a structural model of a 12-base pair duplex of B-form DNA.) In it nucleic acid bases are stacked in pairs one on top of the other with a slight twist reminiscent of a spiral staircase [16]. The unique stacking and overlapping of the n- and Tr-electrons of DNA bases may provide a preferred path for electron transfer. Similarly, the exceptional closeness of the stacked bases may have important consequences for charge motion in DNA duplexes. Additionally, the... 

For this reason, the Casimir formulation had another far-reaching effect. It made us recognize that "zero-point" electromagnetic-field fluctuations in a vacuum are as valid as fluctuations viewed in terms of charge motions.11 As clearly predicted by the... 

Resonance frequencies or absorption frequencies occur when the natural frequencies of charge motion are close to the frequencies of the applied fields. It is no surprise that absorption frequencies are what show up in forces that depend on spontaneous charge fluctuation (see Fig. L2.23). 

Photorefractive Polymers Polymers that are used to write and read information through their characteristics of charge, motion and nonlinear optical response. 

Fig. 3. Energy levels in AgX. Ey = valence band Ec = conduction band. Exposure process A light absorption B charge motion to traps C trapped charges D latent image...

The transverse charge motion is incoherent for a quasi-one-dimensional conductor as long as the condition h hiT is fulfilled (where the intrachain scattering time provides a broadening to the quasi-one-dimensional Fermi surface). This situation is encountered at high temperature. The interchain hopping rate is thus determined by the one-dimensional Fermi golden rule [60] ... 

NMR is a valuable structural tool because the observed resonance frequency vq depends on the molecular environment as well as on y and Bq. The electron cloud that surrounds the nucleus also has charge, motion, and, hence, a magnetic moment. The magnetic field generated by the electrons alters the Bq field in the microenvironment around the nucleus. 

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