Dynamics of late-stage phase separation in crystalline solids

The dynamics of Ostwald ripening in elastically stressed crystalline solids is determined through large-scale numerical simulations. Using the insight provided by the simulations, a theory for the dynamics of late-stage phase separation in elastically anisotropic homogeneous solids is developed. Both the theory and simulations show that for the systems considered elastic stress does not alter the exponent of the temporal power law for the average particle size but does affect the amplitude of the power law in a manner that is only a function of the symmetry of the particle morphology.     

Stability of polar oxide surfaces

The structures of the polar surfaces of ZnO are studied using ab initio calculations and surface x-ray diffraction. The experimental and theoretical relaxations are in good agreement. The polar surfaces are shown to be very stable; the cleavage energy for the (0001)-Zn and (0001;)-O surfaces is 4.0 J/m(2) comparable to 2.32 J/m(2) for the most stable nonpolar (1010) surface. The surfaces are stabilized by an electronic mechanism involving the transfer of 0.17 electrons between them. This leads to 2D metallic surface states, which has implications for the use of the material in gas sensing and catalytic applications.     

A study of LaCoO3 by UV photoelectron spectroscopy

He(II) photoelectron spectra of LaCoO₃ and La_0.7Sr_0.3CoO₃ have been recorded. Spectra of LaCoO₃ were recorded at various temperatures in the range 77 K ? T ? 873 K and changes in the spectra were observed corresponding to the variation of the Co spin state in the lattice.     

Bis(2,2′-bipyridyl)diisopropoxomolybdenum(II): A spin-state equilibrium for a complex of a second-row transition element

The variation of magnetic moment with temperature displayed by cis-[Mo(OPrⁱ)₂(bipy)₂] shows that the complex exists in an equilibri     

Mass excesses of60, 62Fe,68Ni,69Cu,74Zn,73, 75Ga

Accurate, confirmed mass excess values have been determined for the nuclei^{60, 62}Fe,⁶⁸Ni,⁶⁹Cu, and^{73, 75}Ga by theQ-value method. The mass of⁷⁴Zn requires further study. Good agreement was found between experimentally determined mass values and those from mass model predictions.     

Search for resonances in 12C(9Be, α)17O

Excitation functions at 7° (lab) have been measured from E_c.m. = 5.1 to 11.4 MeV in approximately 114 keV steps for 15 groups of final states in ¹⁷O populated by the ¹²C(⁹Be, α) reaction. Statistical tests have been used to locate possible non-statistical structure in the excitation functions. Possible anomalies were found near E_c.m. = 6.3, 7.5, 8.9 and 9.7 MeV. Angular distributions were measured at E_c.m. = 9.20, 9.71 and 10.23 MeV for the three lowest excited states in ¹⁷O. The data have been compared with Hauser-Feshbach calculations in addition to the following reaction mechanisms: compound plus a single resonance, compound plus interfering resonances and compound plus direct reactions.     

K1(890) production in K−p → NKπ at 16 GeV/c

Results on $\text{K}{}^1\text{(890)}$ production in K^?p → NKπ reactions at 16 GeV/c are presented. Total cross sections, differential cross sections and density matrix elements are determined. It is found that: (i) The cross section for K^1?(890) p is consistent with containing two components, one due to natural parity exchange, falling slowly with increasing energy, the other, due to unnatural parity exchange, vanishing rapidly with increasing energy. For $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>o</mtext>}}\text{(890)}\text{n}$, the cross section decreases steadily as the energy increases. (ii) Natural spin-parity exchange dominates in the K^1?(890) p channel, the unnatural exchange contribution being approximately (5±4)%. In $\text{K}{}^{\mathrm{<mtext>1</mtext><mtext>o</mtext>}}\text{(890)}\text{n}$, natural spin-parity exchange is only about (30±10)%. (iii) The reacton $\text{K}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^{\mathrm{1?}}\text{(890)}\text{p}$ is dominated (95±5)% by isoscalar exchange. (iv) The effective trajectory involved in the I = 0 natural parity exchange is consistent with the ω-f trajectory. (v) Interference terms between exchanges with positive (f, π^o,…) and negative (?^o, ω,…) C-conjugation amount to (23±12) μb at 16 GeV/c.     

Search for substructure in pp total cross section in the 2200 MeV mass region

The $\text{p}$p total cross section was measured from 2130 to 2250 MeV with mass resolution 2.25 MeV (FW). No fine structure was found with σΓ above the statistical limit of 7 MeV mb. A spin J particle coupled to the $\text{p}$p system must have partial width less than $\text{1.8}\text{(2J+1)}$ MeV.