Berry phase for a spin 1/2 particle in a classical fluctuating field

The effect of fluctuations in the classical control parameters on the Berry phase of a spin 1/2 interacting with an adiabatically cyclically varying magnetic field is analyzed. It is explicitly shown that in the adiabatic limit dephasing is due to fluctuations of the dynamical phase.

Connections between Classical and Parametric Network Entropies

This paper explores relationships between classical and parametric measures of graph (or network) complexity. Classical measures are based on vertex decompositions induced by equivalence relations. Parametric measures, on the other hand, are constructed by using information functions to assign probabilities to the vertices. The inequalities established in this paper relating classical and parametric measures lay a foundation for systematic classification of entropy-based measures of graph complexity.

OXOIRON(IV) PORPHYRINS DERIVED FROM CHARGED IRON(III) TETRAARYLPORPHYRINS AND CHEMICAL OXIDANTS IN AQUEOUS AND METHANOLIC SOLUTIONS

The oxidation of six charged iron(III) tetraarylporphyrins with chemical oxidants has been investigated. In aqueous solution each can be converted by tert-butyl hydroperoxide or monopersulphate into its corresponding oxoiron(IV) porphyrin, whereas in methanol only the iron(III) tetra(N-methylpyridyl)porphyrins form detectable ferryl porphyrins at ambient temperatures. On standing, the iron species revert to the parent porphyrin with a small loss due to non-reversible oxidative destruction. That the oxidised porphyrin intermediates are oxoiron(IV) species has been determined using UV-VIS, resonance Raman, H1 NMR and EPR spectroscopy.

Transport properties of protic ionic liquids, pure and in aqueous solutions: Effects of the anion and cation structure

Ionic conductivities of twelve protic ionic liquids (PILs) and their mixtures with water over the whole composition range are reported at 298.15 K and atmospheric pressure. The selected PILs are the pyrrolidinium-based PILs containing nitrate, acetate or formate anions; the formate-based PILs containing diisopropylethylammonium, amilaminium, quinolinium, lutidinium or collidinium cations; and the pyrrolidinium alkylcarboxylates, [Pyrr][CnH2n+1COO] with n = 5–8. This study was performed in order to investigate the influence of molecular structures of the ions on the ionic conductivities in aqueous solutions. The ionic conductivities of the aqueous solutions are 2–30 times higher than the conductivities of pure PILs. The maximum in conductivity varies from ww=0.41???to???0.74 and is related to the nature of cations and anions. The molar conductance and the molar conductance at infinite dilution for (PIL + water) solutions are then determined. Self-diffusion coefficients of the twelve protic ionic liquids in water at infinite dilution and at 298.15 K are calculated by using the Nernst–Haskell, the original and the modified Wilke–Chang equations. These calculations show that similar values are obtained using the modified Wilke–Chang and the Nernst–Haskell equations. Finally, the effective hydrodynamic (or Stokes) radius of the PILs was determined by using the Stokes–Einstein equation. A linear relationship was established in order to predict this radius as a function of the anion alkyl chain length in the case of the pyrrolidinium alkylcarboxylates PILs.