Edge energy

Surface Stresses and Edge Energies. Some surface tension values, that is, values of the surface stress t, are included in Table VII-2. These are obtained by applying Eq. Vll-5 to the appropriate lattice sums. The calculation is very sensitive to the form of the lattice potential. Earlier calculations have given widely different results, including negative r [43, 51, 52]. 

It might be noted that only for particles smaller than about 1 /ig or of surface area greater than a few square meters per gram does the surface energy become significant. Only for very small particles does the edge energy become important, at least with the assumption of perfect cubes. 

Side (cm) Total Area (cm ) Total Edge (cm) Surface Energy (ergs/g) Edge Energy (ergs/g)... 

Fig. 1. Band-edge energy diagram where the energy of electrons is higher in the conduction band than in the valence band (a) an undoped semiconductor having a thermally excited carrier (b) n-ty e doped semiconductor having shallow donors and (c) a -type doped semiconductor having shallow acceptors.

The wavenumber is defined at a photon energy E above the absorption edge energy Eq, with respect to the mass of the electron m. ... 

The discovery of a new heterodinuclear active site in [NiFe] hydro-genases opens the way for the proposal of catalytic cycles based on the available spectroscopic data on the different active site redox states, namely EXAFS studies that reveal that the Ni-edge energy upon reduction of the enzyme supports an increase in the charge density of the nickel (191). 

Flood R, Enright B, Allen M, Barry S, Dalton A, Doyle H, Tynan D, Eitzmaurice D (1995) Determination of band edge energies for transparent nanocrystaUine TiOa-CdS sandwich electrodes prepared by electrodeposition. Sol Energy Mater Sol Cells 39 83-98... 

The main problem with this explanation for tubule formation arises from its prediction for the dimensions of the cylinder. In this model, the energy of a cylinder comes from two sources the curvature of the entire membrane and the edge energy of the membrane edge exposed to the solvent. These mechanisms give... 

Interfacial Tension. The interfacial energy a between a crystal and an aqueous solution cannot (at least in general) be measured by macroscopic methods. But it may be deduced from homogeneous nuclea-tion data (20-24). For the purpose of determining the edge energy Y = a CT one may either take the individual value determined on the actual substance (if it is determined) or use the general correlation with the solubility cs, expressed for instance by (10,18)... 

Edge-energy shifts as a probe of Ni redox chemistry... 

Fig. 16.7 Plutonium L -edge XANES spectra plotted with respect to the relative XANES edge energy for sorbed Pu on Yucca Mountain tuff at 6 months and 2 years. All spectra taken after two years indicated an average oxidation state of Pu(IV) those taken after 6 months had average oxidation states predominantly of Pu(V) and Pu(VI). Reprinted with permission from Powell BA, Duff MC, Kaplan DI, Field RA, Newville M, Hunter BD, Bertsch PM, Coates JT, Serkiz SM, Sutton RS, Triay IR, Vaniman DT (2006) Plutonium oxidation and subsequent reduction by Mn(IV) minerals in Yucca Mountain tuff. Environ Sci Technol 40 3508-3514. Copyright 2006 American Chemical Society...

The absolute K edge energy was determined by reference to V Og, which was run repeatedly to confirm edge position. The identity and crystallographic purity of the reference samples (both purchased and in-house preparations) were confirmed by x-ray diffraction and were used without further treatment. 

It should be noted that the absolute energy calibrations of beamlines vary. Determining the peak position of an element within a protein relative to a known standard (such as the metallic form of that element) can save time in future structural experiments. Accurate determination of absorption edge energies for various metals has been reported by Kraft et al. (1996). 

Kraft, S., Stilmpel, J., Becker, P. and Kuetgens, U. (1996). High resolution x-ray absorption spectroscopy with absolute energy calibration for the determination of absorption edge energies. Rev. Set. Instrum. 67,681-687. 

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