Charge ordering, electronic

Key words tetragonal tungsten bronze, charge ordering, electron diffraction... 

Another property that is related to chemical hardness is polarizability (Pearson, 1997). Polarizability, a, has the dimensions of volume polarizability (Brinck, Murray, and Politzer, 1993). It requires that an electron be excited from the valence to the conduction band (i.e., across the band gap) in order to change the symmetry of the wave function(s) from spherical to uniaxial. An approximate expression for the polarizability is a = p (N/A2) where p is a constant, N is the number of participating electrons, and A is the excitation gap (Atkins, 1983). The constant, p = (qh)/(2n 2m) with q = electron charge, m = electron mass, and h = Planck s constant. Then, if N = 1, (1/a) is proportional to A2, and elastic shear stiffness is proportional to (1/a). 

When the combined system of adatom and substrate is in its ground state, so that the lowest energy levels are each doubly occupied with an a- and a /2-spin electron, then, if two electrons are in a localized level, a localized surface bond will be formed. However, if the localized level is unoccupied, then an adbond formation will be achieved without localization of the bonding electrons (i.e., only delocalized electrons will be involved in the adbond). In the case of electron localization, the type of adbond is determined by the charge order of the adatom state, namely,... 

LD. ff is in the order of 100 nm. In contrast, the thickness of the accumulation and inversion layers, in which the mobile charge carriers (electrons or holes) are concentrated, is in the order of 5 to 10 nm and is much thinner than the thickness of the depletion layer. 

We now consider a transfer reaction of charged particles across the interface of electrodes. For a hydrated particle in aqueous solution, the electrochemical potential of the particle is independent of the electrode potential, though it depend on the activity of the partide (the concentration of the partide), regardless of whether the partide is charged (ion) or noncharged (neutral partide). In contrast, for a charged particle (electron or ion) in the electrode, the electrochemical potential of the particle depends on both the electrode potential E and the absolute activity Xk Pk = A7 lnXk-i-zeE. From Eqn. 7-34 we then obtain Eqn. 7-35 for the reaction order, Ck, with respect to a charged particle k in the electrode if the activity of k is constant ... 

CHARGE ORDERING AND TILT MODULATION IN MULTIFERROIC FLUORIDES WITH TTB STRUCTURE BY ELECTRON DIFFRACTION AND SINGLE CRYSTAL XRD... 

Response temperature (operating temperature) may decrease in the foUowing order bond formation and cleavage —> molecular deformation lattice deformation —> electronic deformation such as SDW and charge-order melting. 

Tajima N, Sugawara N, Tamura M, Nishio Y, Kajita K (2006) Electronic phases in an organic conductor a-(BEDT-TTF)2l3 ultra narrow gap semiconductor, superconductor, metal, and charge-ordered insulator. J Phys Soc Jpn 75 051010/1-10... 

The solvation dynamics following charge-transfer electronic excitation of diatomic solutes immersed in a methanol-water mixture provides a direct window on the molecular changes occurring upon solvent substitution. The solvation response of the mixtures is separated into methanol and water contributions in order to elucidate the role played by each molecular species on the solvation dynamics. Significandy different responses for the two solutes are found and related to the fact that the solute with the smaller site diameters is a much better hydrogen (H)-bond acceptor than the larger diameter solute (Skaf and Ladanyi, 1996). 

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