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We theoretically investigate the contribution of the excited state to the ellipticity of the harmonics from H2+ at different orientation angles irradiated by a linearly polarized laser pulse. It is found that the first excited state has a significant influence to the ellipticity of the harmonics, and the contribution of higher excited states to the ellipticity can be neglected. Moreover, the conclusion is not dependent on the laser intensity. [ABSTRACT FROM AUTHOR]

X-ray absorption spectra (XAS) at Mn K-edge and Fe K-edge in LaMn1−xFexO3 show that with the increase of Fe substitution the chemical valence of Mn4+ decreases, while the chemical valence of Fe3+ remains unchanged. Structural distortions, such as the rotating and tilting for oxygen octahedron in the unit cell vary with iron content. A phase transition occurs at the Fe content values of 0.2∼0.3. The evolutions of rotation and tilting angle of FeO6/MnO6 octahedral may be the vital factors to the structure and magnetism. We believe that the spin configuration of Fe3+ may vary from the intermediate spin t42ge1g (S = 3/2) to the higher spin t32geg2 (S = 5/2) near the phase transition. [ABSTRACT FROM AUTHOR]

The ionization time in sequential double ionization with an elliptically polarized laser pulse has been examined theoretically using a semiclassical method. The significant discrepancy between the ionization time for parallel and anti-parallel electron emission is predicted numerically for the first time. The impact of the carrier envelope phase offset is also studied in this work. [ABSTRACT FROM AUTHOR]

The twisted intramolecular charge transfer and the excited state relaxation of 1-aminoanthraquinone (1-NH2-AQ) in different solvents are investigated using quantum chemical calculations in this paper. The geometries of the ground state are optimized both in gas and solvents based on the high-level ab initio calculations, the lowest excited singlet state geometry is optimized only in gas for simplicity. An intramolecular charge transfer property is substantiated by the large change of dipole moments between the S0 and S1 states. The mechanism of twisted intramolecular charge transfer is proposed by the conformational relaxation on the potential surface of the S1 state. Quantum chemical calculations present that internal conversion and intersystem crossing are important approaches to the ultrafast deactivation of the S1 state via the twisting of the amino group. The smaller energy difference between the S0 and S1 state shows that the internal conversion process is much faster in a polar solvent than in a nonpolar solvent. Energy intersections between the T2 and S1 state in cyclohexane and dioxane indicate a faster intersystem crossing process in them than in ethanol. These theoretical results agree well with the previous experimental results. Energy barriers are predicted on the potential surface of the S1 state, and they have a positive correlation to solvent viscosity, and the timescale of twisted intra-molecular charge transfer in dioxane is predicted to be longer than in cyclohexane and ethanol. [ABSTRACT FROM AUTHOR]

La2/3Sr1/3MnO3 films are deposited on (001) silicon substrates, in which the silicon surfaces have artificially been treated into the scallops-like, pyramid-like, and smooth polishing structure, by pulsed laser deposition. The magnetoresistances of the films on etched substrates under low applied field are very sensitive to the applied field, and much larger (14.3% for acid-etched, and 42.9% for alkali-etched) than that on the polished Si at 5 K. Zero-field-cooled and field-cooled magnetization behaviors are measured and analyzed. Remarkable upturn behaviors in temperature-dependent resistivity for all samples are observed at low temperature, which follows the Efros–Shkloskii variable range hopping law and the Arrhenius law. We believe that the rough surface may be useful in device design. [ABSTRACT FROM AUTHOR]

The influence of strain distribution on morphology evolution of Ge/GeO2 core/shell nanoparticle confined in ultrathin Al2O3 thin film by surface oxidation is investigated. A finite-element simulation is performed to simulate the morphology evolution of the confined Ge/GeO2 core/shell nanoparticle under the influence of the local strain distribution. It indicates that the resultant oxidation-related morphology of Ge/GeO2 core/shell nanoparticle confined in ultrathin film is strongly dependent on the local strain distribution. On the other hand, the strain gradients applied on the confined GeO2 shell can be modified by the formation of polycrystalline GeO2 shell, which has potential application in tailoring the microstructure and morphology evolution of the Ge/GeO2 core/shell nanoparticle. [ABSTRACT FROM AUTHOR]

We characterize the structures of Ge1–xSnx films with x up to 0.14 grown on Ge (00l) by molecular-beam epitaxy at low temperature. The results show that Ge1–xSnx films are fully strained even at high Sn composition. The in-plane lattice parameters remain exactly the same as that of the substrate. Depth sensitivity analysis of the lattice parameters indicates that the strains of the epitaxial films are all in homogeneity. The films are fully strained. Poisson ratios, the force constants for the bonds between Ge and Sn are estimated and discussed in the present paper. Raman results show Ge—Ge, Ge—Sn, Sn—Sn vibrational modes. The Sn—Sn bond aggregation may respond to the high quality of our films. The fully strained epitaxy films with high content of Sn may be useful in designing the high quality GeSn films. [ABSTRACT FROM AUTHOR]

The VUV double photoionizations of small molecules (NO, CO, CO2, CS2, OSC and NH3) were investigated with photoionization mass spectroscopy using synchrotron radiation. The double ionization energies of molecules were determined with photoionization efficiency spectroscopy. The total energies of these molecules and their parent dications (NO2+, CO2+, CO2+2, CS2+2, OSC2+ and NH2+3) were calculated using the Gaussian 03 program and Gaussian 2 calculations. Then, the adiabatic double ionization energies of the molecules were predicated by using high accuracy energy mode. The experimental double ionization energies of these small molecules were all in reasonable agreement with their respective calculated adiabatic double ionization energies. The mechanisms of double photoionization of these molecules were discussed based on a comparison of our experimental results with those predicted theoretically. The equilibrium geometries and harmonic vibrational frequencies of molecules and their parent dications were calculated by using the MP2 (full) method. The differences in configurations between these molecules and their parent dications were also discussed on the basis of theoretical calculations. [ABSTRACT FROM AUTHOR]