Monotonous and oscillatory recombination kinetics in neutron irradiated crystalline chromates

Abstract

Kinetics of post recoil thermal annealing of chromate salts after ⁵⁰Cr(n, γ)⁵¹Cr nuclear reaction reveals a monotonous and an oscillatory part amounting 1–2% of the total retention. The permanent recombination after subtracting the oscillatory part has been found to consist of two first order processes producing ⁵¹Cr(VI) from ⁵¹Cr(III) during the examined first hour. The oscillatory phenomenon is possibly explained by thermodynamics of irreversible processes.     

Optical and structural comparison between nitrogen-doped and oxygen-rich ZnO thin films

A ZnO thin film reactively sputtered at high oxygen pressure (O-rich) was compared to a nitrogen-doped ZnO (ZnO:N) thin film using optical and structural spectroscopies. X-ray diffraction measurements confirmed a high (0002) preferential orientation for both films. Absorption measurements revealed two intra-band-gap absorptions in addition to observed free exciton (FX) and neutral acceptor–bound exciton features in both films. Binding energies of the FXs were calculated to be 65 and 69 meV, respectively, for the ZnO:N and O-rich thin films at 15 K. Photoluminescence measurements revealed nearly the same characteristics, i.e. that the deep level emission is dominant. Recombination lifetime values of 577.35 and 797.46 ps were measured for ZnO:N and O-rich thin films, respectively.     

壁面催化对再入飞行器等离子体鞘套及电磁参数的影响

针对超高声速流动中的高温真实气体效应,采用数值模拟求解考虑化学非平衡的三维Navier-Stokes(N-S)方程,研究了壁面催化对典型再入飞行器等离子体鞘套及电磁参数的影响规律.研究发现:(1)完全催化壁条件下等离子体密度计算结果与飞行试验符合较好;(2)完全催化壁条件下,离解原子在壁面的复合导致波后气体可压缩性增强...     

Au激光等离子体的双电子复合速率系数

基于准相对论多组态HartreeFock理论和扭曲波近似,采用组态平均的方法,从头计算了类铁金离子类镓金离子的双电子复合速率系数,计算中包含了大量稠密的自电离能级,由于宽广的自电离能级分布和极其复杂的级联效应,造成高Z材料Au的双电子复合速率系数不同于低Z元素的特征,与现有文献的类镍金离子比较,结果表明,在“神光Ⅱ”实验装置诊断的电子温度约为2keV,电子密度约为6×1021cm-3,Au激光等离子体不同理论之间的双电子复合速率系数误差不到10%.这对于使用超组态碰撞辐射模型模拟Au的激光等离子体M带细致 关键词： 双电子复合 类铁金离子类镓金离子 复合速率系数     

Systematic theoretical study of dielectronic recombination for helium-like isoelectronic sequence

Dielectronic recombination cross sections and rate coefficients of He-like isoelectronic sequence are systematically calculated employing the relativistic Flexible Atomic Code (FAC). The calculated DR resonance strengths, cross sections and rate coefficients are in good agreement with other experimental and theoretical results. The effects of radiative cascades on DR cross sections and the variation of DR branching ratio with different DR resonance and atomic numbers Z are studied. The n⁻³ scaling law is also checked and used to extrapolate rate coefficients. And analytic formulas are used to fit the total rate coefficients with respect to both T and Z for helium-like isoelectronic sequence.     

The oxygen isotope effect on the infrared photo-induced absorption spectra of La2CuO4

The infrared photo-induced spectra of the isotope-substituted stoichiometric La₂CuO₄ samples were studied at T=20 K. Measured spectra were analyzed within the small polaron hopping theory. A small, but detectable shift of the effective phonon frequency on the substitution ¹⁶O to ¹⁸O is found for the high-energy surface carrier associated band (~4000 cm^-1) and has a value of α_O = 0.3 ±0.2. The low-energy band (~1500 cm^-1) originating from the bulk carriers doesn't show any difference within experimental error which is fully in agreement with theory predictions. The isotope shifts of the optically active oxygen-related phonon modes are described well by the harmonic approximation.     

Photoluminescence of a BaSiO3:Yb3+ crystal

We present the results of a study of the luminescence and luminescence excitation spectra, and also the luminescence kinetics of a BaSiO₃:Yb³⁺ crystal. We have established the mechanism for emission by the matrix and energy transfer from the matrix to the rare earth ion. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 478–482, July–August, 2006.     

有机电致发光器件中载流子的输运和复合发光

以高场作用下载流子对三角势垒的FowlerNordheim隧穿理论为基础,建立了单层有机电致发光器件中载流子输运和复合发光模型,给出了薄膜中电子空穴对的解离和复合概率及电子和空穴的密度分布.计算并讨论了外加电压和注入势垒对器件电流和复合效率的影响. 关键词： 电致发光器件 载流子输运 载流子复合