Spin Dependence of Interfacial Reflection Phase Shift at Cu/Co Interface

The spin dependent reflection at the interface is the key element to understand the spin transport. By completely solving the scattering problem based on first principles method, we obtained the spin resolved reflectivity spectra. The comparison of our theoretical results with experiment is good in a large energy scale from Fermi level to energy above vacuum level. It is found that interfacial distortion is crucial for understanding the spin dependence of the phase gain at the Cu$|$Co interface. Near the Fermi level, image state plays an important role to the phase accumulation in the copper film.Comment: 6 papges, 3 figures, accepted by Physical Review

Hyperconjugative Effect on the Electronic Wavefunctions of Ethanol

Hyperconjugation is a basic conception of chemistry. Its straightforward effect is exhibited by the spatial delocalization characteristics of the electron density distributions or wavefunctions. Such effects on the electron wavefunctions of the highest-occupied molecular orbitals (HOMO) of two ethanol conformers are demonstrated with electron momentum spectroscopy together with natural bond orbital analyses, exhibiting the distinctly different symmetries of the HOMO wavefunctions in momentum space.Comment: 3 Figures, 1 Scheme. Submitte

Overtone spectra and intensities of tetrahedral molecules in boson-realization models

The stretching and bending vibrational spectrum and the intensities of infrared transitions in a tetrahedral molecule are studied in two boson-realization models, where the interactions between stretching and bending vibrations are described by a quadratic cross term and by Fermi resonance terms, called harmonically coupled and Fermi resonance boson-realization model, respectively. The later is a development of our recent model. As an example, the two models are applied to the overtone spectrum and the intensities of silicon tetrafluorde. Those models provide fits to the published experimental vibrational eigenvalues with standard deviations 1.956 cm$^{-1}$ and 0.908 cm$^{-1}$, respectively. The intensities of infrared transitions of its complete vibrations are calculated in the two models, and results show a good agreement with the observed data.Comment: 14 pages Revtex, no figure, to appear in Annals of Physic

RF-thermal-structural-RF coupled analysis on the travelling wave disk-loaded accelerating structure

Travelling wave (TW) disk-loaded accelerating structure is one of the key components in normal conducting (NC) linear accelerators, and has been studied for many years. In the design process, usually after the dimensions of each cell and the two couplers are finalized, the structure is fabricated and tuned, and then the whole structure characteristics can be measured by the vector network analyzer. Before the structure fabrication, the whole structure characteristics are less simulated limited by the available computer capability. In this paper, we described the method to do the RF-thermal-structural-RF coupled analysis on the TW disk-loaded structure with one single PC. In order to validate our method, we first analyzed and compared our RF simulation results on the 3m long BEPCII structure with the corresponding experimental results, which shows very good consistency. Finally, the RF-thermal-structure-RF coupled analysis results on the 1.35m long NSC KIPT linac accelerating structure are presented.Comment: 5 pages, 16 figures, Submitted to the Chinese Physics C (Formerly High Energy Physics and Nuclear Physics

Recombinant expression and functional analysis of a Chlamydomonas reinhardtii bacterial-type phosphoenolpyruvate carboxylase gene fragment

To investigate the function of a bacterial-type phosphoenolpyruvate carboxylase (PEPC2) derived from photosynthetically-grown Chlamydomonas reinhardtii, a fragment of the pepc2 gene was cloned and expressed in Escherichia coli. After optimal induction for 6 h, PEPC activity in the reverse mutant was lower than wild type (0.9 vs. 1.7 U/mg protein), and soluble protein was also lower than wild type (119 vs. 186 mg/g dry wt). In contrast, the total lipid content was increased from 56 (in wild type) to 71 mg/g dry wt, despite the growth rate being slightly diminished. The changes in PEPC activity, soluble protein and total lipid in the forward mutant were the opposite (2.4 U/mg, 230 mg/g, and 44 mg/g dry wt, respectively). Together, these data indicate that PEPC may function as a metabolic pivot in the regulation of protein and lipid accumulation in this alga

On the measurement of surface diffusivity in disordered nanoporous carbon via molecular dynamics simulations

Gas diffusion in nanoporous carbon includes distinct diffusion modes: surface diffusion on the pore walls and non-surface diffusion away from pore walls. We have performed molecular dynamics (MD) simulations of Ar diffusion in disordered nanoporous carbon. The main objective of this work is to separate the surface diffusion and non-surface diffusion contributions so as to comprehend their respective dependency on the porous structure and testing conditions. The nanoporous carbon sample is obtained using the quenched molecular dynamics (QMD) method. Gas flows are generated by applying a constant external force on each Ar atom, mimicking a constant chemical potential gradient. The contributions from surface diffusion and non-surface diffusion are separated according to the distance of the gas atoms away from the pore wall. We show that the surface diffusivity is affected by the interactions between gas atoms and the pore walls, the temperature, and the loading

Phase Separation and Magnetic Order in K-doped Iron Selenide Superconductor

Alkali-doped iron selenide is the latest member of high Tc superconductor family, and its peculiar characters have immediately attracted extensive attention. We prepared high-quality potassium-doped iron selenide (KxFe2-ySe2) thin films by molecular beam epitaxy and unambiguously demonstrated the existence of phase separation, which is currently under debate, in this material using scanning tunneling microscopy and spectroscopy. The stoichiometric superconducting phase KFe2Se2 contains no iron vacancies, while the insulating phase has a \surd5\times\surd5 vacancy order. The iron vacancies are shown always destructive to superconductivity in KFe2Se2. Our study on the subgap bound states induced by the iron vacancies further reveals a magnetically-related bipartite order in the superconducting phase. These findings not only solve the existing controversies in the atomic and electronic structures in KxFe2-ySe2, but also provide valuable information on understanding the superconductivity and its interplay with magnetism in iron-based superconductors