Defect effect on tribological behavior of diamond-like carbon films deposited with hydrogen diluted benzene gas in aqueous environment

This study examined the friction and wear behavior of diamond-like carbon (DLC) films deposited from a radio frequency glow discharge using a hydrogen diluted benzene gas mixture. The DLC films were deposited on Si (1 0 0) and polished stainless steel substrates by radio frequency plasma-assisted chemical vapor deposition (r.f.-PACVD) at hydrogen to benzene ratios, or the hydrogen dilution ratio, ranging from 0 to 2.0. The wear test was carried out in both ambient and aqueous environments using a homemade ball-on-disk type wear rig. The stability of the DLC coating in an aqueous environment was improved by diluting the benzene precursor gas with hydrogen, suggesting that hydrogen dilution during the deposition of DLC films suppressed the initiation of defects in the film and improved the adhesion of the coating to the interface.     

C2H2 Overtones Near 12300 cm-1 Revisited with a Very Sensitive Cavity Ring-down Spectrometer

利用单模连续的钛宝石激光器, 构建了一台光腔衰荡光谱仪, 其可探测的最小吸收可达1.8×10^-10/cm. 该光谱仪被用来记录C₂H₂分子在12240～12350 cm^-1的泛频光谱. 与在同一波段测量的已报到的CRDS和激光腔内吸收光谱仪结果比较,本测量同时具有更好的灵敏度和精度. 由此,获得了乙炔分子在12290.12、12311.82和12350.61 cm^-1附近高泛频谱带更准确的振转参数     

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用时域有限差分法研究了电磁波在等离子体光子晶体中的传播特性。数值模拟中使用完全匹配层吸收边界条件,计算了电磁波通过等离子体光子晶体的反射和透射系数。讨论了等离子体密度、等离子体温度、介电常数比和引入缺陷层对等离子体光子晶体光子带隙的影响。     

Defect modes and wavelength tuning of one-dimensional photonic crystal with lithium niobate

The defect state of the one-dimensional photonic crystals consisting of lithium niobate and air is theoretically investigated. By applying an external voltage on the defect layer, remarkable wavelength tuning can be achieved. The relation between the wavelength peak and the external voltage is a straight line and the tuning rate is 1.358 nm/kV. The dependence of the wavelength peak on the angle of incidence was also observed at each applied voltage. This feature can be employed to fabricate tunable filters.     

声光调Q激光器所需最小衍射效率的研究

以四能级系统为例, 研究了在输出脉冲能量一定的情况下,声光调Q激光器所需要的最小衍射效率如何确定的问题.通过对调Q反转粒子数密度的求解,获得了调Q激光器输出的一定脉冲能量与腔内损耗、所需最小Q开关的衍射效率和输出镜的反射率等的关系公式.这一结果为声光调Q激光器Q开关衍射效率的设计提供了简便的估算方法.     

脉冲激光辐照光学薄膜的缺陷损伤模型

建立了缺陷吸收升温致薄膜激光损伤模型,该模型从热传导方程出发,考虑了缺陷内部的温度分布以及向薄膜的传导过程,通过引入散射系数简化了Mie散射理论得出的吸收截面.对电子束蒸发沉积的ZrO₂:Y₂O₃单层膜进行了激光破坏实验,薄膜样品的损伤是缺陷引起的,通过辉光放电质谱法对薄膜制备材料的纯度分析发现材料中的主要杂质元素为铂,其含量为0.9％.利用缺陷损伤模型对损伤过程进行了模拟,理论模型和实验结果取得了较好的一致性.     

Cavity shape effect on pKa prediction of small amines

Cavity shape affects the free energy of solvation by which pK_a changes. In this work, we have used different level of theories and basis sets combine with the PCM model of solvation to predict acidity constants of small ammonium ions during their protonation in aqueous solution. Three different kinds of models including UAHF, Bondi, and Pauling have been chosen to study that how a cavity shape changes acidity constant. Contrary to the previous results of literature for bulky ammonium ions, the difference between our results is not very much. Predictions show that in some levels and basis sets UAHF model is the best, while in some other cases it is the worst.     

Thermodynamic quantities and defect equilibrium in La2−xSrxNiO4+δ

In order to elucidate the relation between thermodynamic quantities, the defect structure, and the defect equilibrium in La_2−xSr_xNiO_4+δ, statistical thermodynamic calculation is carried out and calculated results are compared to those obtained from experimental data. Partial molar enthalpy of oxygen and partial molar entropy of oxygen are obtained from δ-P(O₂)-T relation by using Gibbs-Helmholtz equation. Statistical thermodynamic model is derived from defect equilibrium models proposed before by authors, localized electron model and delocalized electron model which could well explain the variation of oxygen content of La_2−xSr_xNiO_4+δ. Although assumed defect species and their equilibrium are different, the results of thermodynamic calculation by localized electron model and delocalized electron model show minor difference. Calculated results by the both models agree with the thermodynamic quantities obtained from oxygen nonstoichiometry of La_2−xSr_xNiO_4+δ.     

Investigations on the local angular distortions and the spin-Hamiltonian parameters for Ni in sulfides

The local angular distortions and the spin-Hamiltonian parameters (the g factors and the hyperfine parameters) for Ni⁺ in ABS₂ (ACu, Ag; BAl, Ga) ternary sulfides are theoretically investigated from the perturbation formulas of these parameters for 3d⁹ ions in a tetragonally distorted tetrahedron. In view of the strong covalency of such systems, the ligand orbital and spin–orbit coupling contributions are taken into account using the cluster approach. The local impurity-ligand bond angles in the Ni⁺ centers are found to be about 1.4–4.5° smaller than those of the host monovalent A sites in the pure crystals, due to size mismatching substitution. As a result, the ligand tetrahedra exhibit slight elongation in CuBS₂:Ni⁺ and slight compression in AgGaS₂:Ni⁺. The calculated spin-Hamiltonian parameters, optical transitions and the relative intensity ratios show reasonable agreement with the experimental data.     

Cavity Ring Down Laser Absorption Spectroscopy of Nil

The absorption spectrum of NiI between 445 and 510 nm has been investigated using the technique of laser vaporization/reaction with free jet expansion and cavity ring down laser absorption spectroscopy. Two new transitions namely,[21.3]^2△5/2-X^2△5/2 and [21.9]^2Ⅱ3/2-X^2△5/2 systems were identified and studied. Spectra of both ^58NiI and ^60NiI isotopic molecules were observed. Equilibrium molecular constants for both electronic states are reported and the equilibrium bond length for the [21.3]^2△5/2 state and the[21.9]^2Ⅱ3/2 state was respectively determined to be 2.431 and 2.481 A.