A b initio calculation of the growth of Te nanorods and Bi2Te3 nanoplatelets

In this paper the growth mechanism of a Te/Bi2Te3 novel structure is studied by ab-initio calculations. The results show that the growth of Te nanorods is determined by the adsorption energy of Te atoms on different crystalline Te surfaces. The adsorption energy of Te on the Te （001） surface is 3.29 eV, which is about 0.25 eV higher than that of Te on the Te （110）. This energy difference makes the preferential growth direction along the 〈 001 〉 direction. In addition, the higher surface energy of Bi2Te3 （110） and the lattice misfit between crystalline Bi2We3 and Te along 〈 001 〉 direction are considered to explain the growth of the Bi2Te3 nanoplatelets, in which Volmer-Weber model is used. The theoretical results are in agreement with experimental observation.     

1-W, high-repetition-rate room temperature operation of mid-infrared optical parametric oscillator based on periodically poled MgO-doped LiNbO

In this paper a high-repetition-rate mid-infrared （mid-IR） optical parametric oscillator based on periodically poled MgO-doped LiNbO3 （PPMgLN） at room temperature was demonstrated. The maximum average mid-IR output power at 3.63μm was 1.02 W with the repetition rate of 60kHz and corresponding efficiency from the pump to the idler was 26.7%. The temperature tuning and the period tuning characteristics were also discussed.     

Continuous-wave mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate

This paper reports a continuous-wave （CW） mid-infrared intracavity singly resonant optical parametric oscillator based on periodically poled lithium niobate （PPLN） pumped by a diode-end-pumped CW Nd：YVO4 laser. Considering the thermal lens effects, it adopted an optical ballast lens and the near-concentric cavity for better operation. At the PPLN＇s grating period of 28.5 μm and the temperature of 140℃, the maximum idler output power of 155 mW at 3.86 μm has been achieved when the 808 nm pump power is 8.5 W, leading to an optical-to-optical conversion efficiency of 1.82%.     

Re-research on the size of proto-neutron star in core-collapse supernova

The electron capture timescale may be shorter than hydrodynamic timescale in inner iron core of core-collapse supernova according to a recent new idea. Based on the new idea, this paper carries out a numerical simulation on supernova explosion for the progenitor model Ws15M. The numerical result shows that the size of proto-neutron star has a significant change （decrease about 20%）, which may affects the propagation of the shock wave and the final explosion energy.     

The origin of blue photoluminescence from nc-Si/SiO2 multilayers

Intensive blue photoluminescence （PL） was observed at room temperature from the nanocrystalline-Si/SiO2 （nc-Si/SiO2） multilayers （MLs） obtained by thermal annealing of SiO/SiO2 MLs for the first time. By controlling the size of nc-Si formed in SiO sublayer from 3.5 to 1.5 nm, the PL peak blueshifts from 457 to 411 nm. Combining the analysis of TEM, Raman and absorption measurement, this paper attributes the blue PL to multiple luminescent centres at the interface of nc-Si and SiO2.     

Line intensities of the asymptotic asymmetric-top radical HO2 at high temperatures

The total internal partition sums were calculated in the product approximation at temperatures up to 5000 K for the asymptotic asymmetric-top HO2 molecule. The calculations of the rotational partition function and the vibrational partition function were carried out with the rigid-top model and in the harmonic oscillator approximation, respectively. Our values of the total internal partition sums are consistent with the data of HITRAN database with -0.14% at 296 K. Using the calculated partition functions, we have calculated the line intensities of υ2 band of HO2 at several high temperatures. The results showed that the calculated line intensities are in very good agreement with those of HITRAN database at temperatures up to 3000 K, which provides a strong support for the calculations of partition functions and line intensities at high temperatures. Then we have extended the calculation to higher temperatures. The simulated spectra of υ2 band of the asymptotic asymmetric-top HO2 molecule at 4000 and 5000 K are also obtained.     

Semiclassical calculation of Rydberg He2^＋ molecular of recurrence spectra ion in a magnetic field

Making use of the molecular closed-orbit theory and a new model potential for the Rydberg molecule, we have calculated the recurrence spectra of He^2＋ molecular ion in a magnetic field for different quantum defects. The Fourier transform spectra of He^2＋ molecular ion may be used to perform a direct comparison between peaks in the spectra and the scaled action values of closed orbits of the excited electron in external fields. We find that the spectral modulations can be analysed in terms of the scattering of the excited electron on the molecular core. Unlike the case of the Rydberg atom where the elastic scattering is predominant, modulations produced by inelastic scattering are also vital to the photoabsorption spectrum of the Rydberg molecule. Our results are in good agreement with the quantum results, which suggests that our method is correct.     

Preparation and luminescence characteristics of Eu^2＋ activated silicate phosphor

This paper synthesizes the Sr2SiO4：Eu^2＋ phosphor by high temperature solid-state reaction. The emission spectrum of Sr2SiO4 ： Eu^2＋ shows two bands centred at 480 and 547 nm, which agree well with the calculation values of emission spectrum, and the location of yellow emission of Sr2SiO4 ： Eu^2＋ is influenced by the Eu^2＋ concentration. The excitation spectrum for 547 nm emission has two bands at 363 and 402 nm. The emission spectrum of white light emitting diodes （w-LEDs） based on Sr2SiO4 ： Eu^2＋ phosphor ＋ InGaN LED was investigated.     

Capability of Raman lidar for monitoring the variation of atmospheric CO2 profile

Lidar （Light detection and ranging） has special capabilities for remote sensing of many different behaviours of the atmosphere. One of the techniques which show a great deal of promise for several applications is Raman scattering. The detecting capability, including maximum operation range and minimum detectable gas concentration is one of the most significant parameters for lidar remote sensing of pollutants. In this paper, based on the new method for evaluating the capabilities of a Raman lidar system, we present an evaluation of detecting capability of Raman lidar for monitoring atmospheric CO2 in Hefei. Numerical simulations about the influence of atmospheric conditions on lidar detecting capability were carried out, and a conclusion can be drawn that the maximum difference of the operation ranges caused by the weather conditions alone can reach about 0.4 to 0.5km with a measuring precision within 30ppmv. The range of minimum detectable concentration caused by the weather conditions alone can reach about 20 to 35 ppmv in vertical direction for 20000 shots at a distance of 1 km on the assumption that other parameters are kept constant. The other corresponding parameters under different conditions are also given. The capability of Raman lidar operated in vertical direction was found to be superior to that operated in horizontal direction. During practical measurement with the Raman lidar whose hardware components were fixed, aerosol scattering extinction effect would be a significant factor that influenced the capability of Raman lidar. This work may be a valuable reference for lidar system designing, measurement accuracy improving and data processing.     

Surface rumples and band gap reductions of cubic BaZrO3 （001） surface studied by means of first-principles calculations

Electronic properties of the （001） surface of cubic BaZrO3 with BaO and ZrO2 terminations have been studied using first-principles calculations. Surface structure, partial density of states, band structure and surface energy have been obtained. We find that the largest relaxation appears in the first layer of atoms, and the relaxation of the BaO-terminated surface is larger than that of the ZrO2-terminated surface. The surface rumpling of the BaO-terminated surface is also larger than that of the ZrO2-terminated surface. Results of surface energy calculations reveal that the BaZrO3 surface is likely to be more stable than the PbZrO3 surface.     

Ab initio study of oxygen-vacancy LaAlO3（001） surface

Density functional theory is used to investigate the surface structures and the energies of two possible terminated LaAlO3 （001） surfaces with oxygen vacancies, i.e. LaO- and AlO2-terminated surfaces. The large displacements of ions, deviated from their crystalline sites, can lead to the formation of the surface rumpling. From thermodynamics analysis, the AlO2-terminated surface with oxygen-vacancies is less stable than the LaO-terminated one. Some states in the gap lie under the Fermi level by about -1eV in the LaO-terminated surface with oxygen vacancies. For the AlO2- terminated oxygen-vacancy surface, some O 2p states move into the mid-gap region and become partially unoccupied. The two types of termination surfaces exhibit conduction related to oxygen vacancies. Our results can contribute to the application of LAO films to high dielectric constant materials.     

Pillow飞片气炮加载实验的数值模拟研究

 采用多介质弹塑性流体动力学计算方法,研制了适用于复杂加载的Lagrange计算程序MLEP,对劳伦斯利弗莫尔国家实验室（Lawrence Livermore National Laboratory,LLNL）19层和冲击波物理与爆轰物理国防科技重点实验室（Laboratory of Shock Wave and Detonation Physics,LSD）设计的29层Mg-Cu体系Pillow密度梯度飞片气炮加载实验过程进行了数值模拟和比较,获得的速度剖面计算结果与实验测试结果吻合一致,验证了流体动力学计算方法、不同材料体系混合模型以及计算程序的有效性和实用性,为进一步开展可控路径的复杂加载实验研究奠定了基础。     

Formation of high density TiN nanocrystals and its application in non-volatile memories

Non-volatile memory based on TiN nanocrystal （TiN-NC） charge storage nodes embedded in SiO2 has been fabricated and its electrical properties have been measured. It was found that the density and size distribution of TiN-NCs can be controlled by annealing temperature. The formation of well separated crystalline TiN nano-dots with an average size of 5 nm is confirmed by transmission electron microscopy and x-ray diffraction, x-ray photoelectron spectroscopy confirms the existence of a transition layer of TiNxOy/SiON oxide between TiN-NC and SiO2, which reduces the barrier height of tunnel oxide and thereby enhances programming/erasing speed. The memory device shows a memory window of 2.5V and an endurance cycle throughout 10^5. Its charging mechanism, which is interpreted from the analysis of programming speed （dVth/dt） and the gate leakage versus voltage characteristics （Ig vs Vg）, has been explained by direct tunnelling for tunnel oxide and Fowler Nordheim tunnelling for control oxide at programming voltages lower than 9V, and by Fowler-Nordheim tunnelling for both the oxides at programming voltages higher than 9V.     

Laser-induced pattern formation from homogeneous polyisoprene solutions

This paper reports that the pattern formation in homogeneous solutions of polyisoprene in toluene saturated with C60 induced by a continuous-wave visible laser is observed experimentally. The transmitted beam patterns change with the increase of the laser irradiation time. In the initial phase, the patterns with concentric ring-shaped structure are formed. In the end, the patterns become speckle-shaped. The incubation time of the transmitted beam widening is inversely proportional to the laser power density and solution concentration. The pattern formation results from the optical-field-induced refractive index changes in the solutions, but the mechanism of optical-field-induced refractive index changes in the polymer solutions needs to be further studied.     

Chemical composition and magnetism of Ag doped LaMnO3

By using a sol-gel clue, a set of polycrystalline perovskite samples La1-xAgxMnO3 with a nominal doping level x ranging from 0.05 to 0.45 has been synthesized. The chemical composition and the magnetism of the samples were investigated. A little Ag was： found seeping from the samples in the sintering process when the doping level exceeded 0.05 and the sintering temperature was higher than 700℃ resulting in the samples being in multiphase. The magnetic transition points of the samples have been found to decrease with increasing sintering temperature. A concentration-dependent Tc similar to that of bivalent metal ion doped perovskite, has been obtained. We believe that the Ag seeping in the sintering process is responsible for those magnetic characteristics.     

Effect of Dy substitution on magnetic properties and magnetocaloric effects of Tb6Co1.67Si3 compounds

The magnetic and magnetocaloric properties of(Tb1-xDyx) 6 Co 1.67 Si 3(0 ≤ x ≤ 0.8) have been experimentally investigated.The compounds exhibit a Ce6Ni2Si3-type hexagonal structure and undergo a second-order magnetic transition.The Curie temperature decreases from ～ 187 K to 142 K as the content of Dy grows from 0 to 0.8.The maximal magnetic entropy change,for a field change of 0-5 T,varies between ～ 6.2 and ～ 7.4 J/kg.K,slightly decreasing when Dy is introduced.The substitution of Dy leads to a remarkable increase in refrigeration capacity(RC).A large RC value of ～ 626 J/kg is achieved for x = 0.4 under a field change of 0-5 T.     

Deceleration of a continuous-wave （CW） molecular beam with a single quasi-CW semi-Gaussian laser beam

We propose a promising scheme to decelerate a CW molecular beam by using a red-detuned quasi-cw semi-Gaussian laser beam （SGB）. We study the dynamical process of the deceleration for a CW deuterated ammonia （ND3） molecular beam by Monte-Carlo simulation method. Our study shows that we can obtain a ND3 molecular beam with a relative average kinetic energy loss of about 10% and a relative output molecular number of more than 90% by using a single quasi-cw SGB with a power of 1.5kW and a maximum optical well depth of 7.33mK.     

Judd--Ofelt analysis of spectra and experimental evaluation of laser performance of Tm3+ doped Lu2SiO5 crystal

This paper reports that the Tm^3＋：Lu2SiO5 （Tm：LSO） crystal is grown by Czochralski technique. The roomtemperature absorption spectra of Tm：LSO crystal are measured on a b-cut sample with 4 at.% thulium. According to the obtained Judd-Ofelt intensity parameters Ω2=9.3155×10^-20 cm^2, Ω4=8.4103×10^-20 cm^2, Ω6=1.5908×10^-20 cm^2, the fluorescence lifetime is calculated to be 2.03 ms for ^3F4 → ^3H6 transition, and the integrated emission cross section is 5.81×10^-18 cm^2. Room-temperature laser action near 2μm under diode pumping is experimentally evaluated in Tm：LSO. An optical-optical conversion efficiency of 9.1% and a slope efficiency of 16.2% are obtained with continuouswave maximum output power of 0.67 W. The emission wavelengths of Tm：LSO laser are centred around 2.06μm with spectral bandwidth of -13.6 nm.     

Self-organization effect in poly（3-hexylthiophene）： methanofullerenes solar cells

This paper studies the self-organization of the polymer in solar cells based on poly（3-hexylthiophene）： [6, 6]-phenyl C61-butyric acid methyl ester by controlling the growth rate of active layer. These blend films are characterized by UV-vis absorption spectroscopy, charge-transport dark J - V curve, x-ray diffraction pattern curve, and atomic force microscopy. The results indicate that slowing down the drying process of the wet films leads to an enhanced selforganization, which causes an increased hole transport. Increased incident light absorption, higher carrier mobility, and balanced carrier transport in the active layer explain the enhancement in the device performance, the power conversion efficiency of 3.43% and fill factor up to 64.6% are achieved under Air Mass 1.5, 100 mW/cm^2.     

Compact efficient optical parametric generator internal to a Q-switched Nd:YVO4 laser with periodically poled MgO:LiNbO3

This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVOquasi-phase-matching, intracavity optical parametric generator, periodically poled MgO-doped lithium niobate (PPMgLN)Project supported by the National Natural Science Foundation of China (Grant Nos 10474071 and 60671036).4265K, 4260F, 4270This paper demonstrates a compact efficient optical parametric generator internal to a Q-switched diode-end-pumped Nd:YVO$_{4}$ laser with periodically poled MgO:LiNbO₃(PPMgLN). With the Q-switch set at a repetition rate of 25kHz and the PPMgLN crystal operated at room temperature (25\du\,), the intracavity optical parametric generator threshold was reached as a diode pump power of 0.9\,W. A maximum signal output power of 0.34W with a pulse width of 25\,ns and a beam quality factor of 1.4 was obtained at an incident diode power of 3.4\,W, leading to a conversion efficiency of 10{\%} with a slope efficiency of 14.4{\%}. By varying the crystal temperature from 25 to 200\du, the output signal wavelengths were tuned in range of 1506--1565\,nm. Over a 30-minutes interval, the instability of the signal power was measured to be less than 1{\%}. In addition, the threshold pump intensity for the intracavity optical parametric generator is theoretically investigated, and the obtained result is in good agreement with the experimental results.