电子磁矩对同步辐射频谱的修正

本文从偶极子辐射场的Heaviside-Feynman表达式出发, 用经典的电动力学方法推导了考虑内禀磁矩影响后的相对论电子辐射频谱分布的表达式, 并对做匀速圆周运动的极端相对论性电子的同步辐射, 计算了两个偏振方向上的考虑磁矩修正后的辐射谱. 计算结果表明对于特征频率为ω_c的同步辐射, 如果ħω_c≥10 keV, 内禀磁矩对辐射的修正是可观的. 通过同步辐射的内禀磁矩修正, 本文讨论了电子束极化度与辐射场偏振度的依赖关系, 并基于此关系提出一种测量电子束极化度的新方法. 关键词： 同步辐射 电子内禀磁矩 同步辐射偏振度 束流极化度     

一种基于强边缘块的时域多分辨率图像分割算法

针对序列图像的变化检测,提出了一种基于强边缘块的时域多分辨率图像分割算法.首先在具有明显边缘特征的图像序列中,提取图像强边缘块的直方图,然后,利用时域多分辨算法,比较不同帧之间的图像差异.这种方法不但能够检测出图像的变化,而且能够确定图像变化的类型.在阈值的选取过程中,采用了自适应阈值方法,实验证明这种方法取得了较好的效果.     

Quantum Correlations in a Family of Two-Qubit Separable States

Quantum correlations in a family of two-qubit separable classical-quantum correlated states are intensively studied with four diferent approaches,namely,quantum discord[Phys.Rev.Lett.88(2002)017901],measurementinduced disturbance(MID)[Phys.Rev.A 77(2008)022301],ameliorated MID[J.Phys.A:Math.Theor.44(2011)352002]and quantum dissonance[Phys.Rev.Lett.104(2010)080501].Quantum correlations captured with diferent approaches are compared and discussed so that their three distinct features are exposed.     

Laser output of radial-slab solid-state laser

In this letter, numerical simulation and experimental study of a radial-slab solid-state laser are presented. The laser includes four crossing-slabs pumped by four Xe flashlamps. The numerical simulation of coherent intensity in the near field and the far field indicates that the laser with the structure can improve the quality of output beam compared with incoherent beam combination. The radial-slab solid-state laser is fabricated, and initial experiments are carried out at a pulse repetition of 1 Hz. Nine beams in the near field and one combined beam in the far field are obtained in our initial experiment. The experimental results are consistent with the numerical analysis in the coherent condition. The results show that coherent beam combination is obtained by this laser.     

Characterization of spectral hole depth in Tm^3＋ ：YAG within the cryogenic temperature range

In this paper, spectral hole depth dependence on temperature below 10 K in Tm^3＋ ：YAG crystal is investigated in detail. A novel model is proposed to analyze the temperature dependence on the spectral hole. By using the proposed model, we theoretically deduce the temperature dependence of spectral hole depth. The results are compared with experimental results and they are in good agreement. According to the theoretic results, the optimum temperature in experiment can be found.     

Interfacial characteristics of Al/Al2O3/ZnO/n-GaAs MOS capacitor

The interfacial characteristics of Al/Al2O3/ZnO/n-GaAs metal-oxide-semiconductor (MOS) capacitor are investigated. The results measured by X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) show that the presence of ZnO can effectively suppress the formations of oxides at the interface between the GaAs and gate dielectric and gain smooth interface. The ZnO-passivated GaAs MOS capacitor exhibits a very small hysteresis and frequency dispersion. Using the Terman method, the interface trap density is extracted from C-V curves. It is found that the ZnO layer can effectively improve the interface quality.     

衰减全反射傅里叶变换红外光谱技术的临床应用研究进展

系统回顾了衰减全反射傅里叶变换红外光谱(attenuated total reflection Fourier transform infrared, ATR-FTIR)技术在临床医学领域中的应用研究进展。ATR-FTIR光谱技术具有实时、简单、无创扫描生物组织样品的优势,通过结合多模式识别统计学方法并对照临床及病理学诊断结果,可对生物组织样本进行判别分析。目前,对甲状腺、乳腺,以及肺组织等新鲜离体组织的光谱学检测中,ATR-FTIR技术可达到较高的判别敏感性、准确性与特异性;尤其在对甲状腺和乳腺疾病患者的前哨淋巴结活检的研究中,应用ATR-FTIR技术,可对良、恶性组织进行敏感性、准确性与特异性均较高的鉴别研究,对辅助临床诊断具有潜在的重要价值。此外,利用ATR-FTIR光谱技术对生物体液进行光谱分析并进一步诊断疾病的研究也在逐步开展。由于血清中所含成分的改变对于提示疾病状况具有重要价值,因而血清ATR-FTIR光谱学诊断方法成为研究热点,已有应用ATR-FTIR技术对脑胶质细胞瘤、心肌梗死、肾衰、阿尔茨海默病、卵巢癌与子宫内膜癌等多种疾病进行分析的研究报道。目前已可通过ATR-FTIR技术对卵巢癌进行疾病分期的判别诊断,该技术有望成为卵巢癌筛查的重要方法。由于血清ATR-FTIR光谱学技术具有检测快速、判别准确、性价比高等优势,有望成为今后生物医学发展的重要方向之一。     

基于激光光解诱导荧光技术实现燃烧反应区及中间产物CH_3瞬态可视化

实现火焰反应区和不同中间组分的在线二维瞬态成像,在湍流燃烧的基础研究中具有十分重要的意义。用Nd∶YAG激光器的5倍频输出(212.8nm)作为光源,通过激光光解诱导荧光技术在甲烷/空气预混火焰中,成功实现了火焰反应区的瞬态成像,并首次采用该技术实现了CH_3的在线瞬态成像测量。分析了该方法同其他荧光标示物在反应区二维瞬态成像方法的优势,并研究了火焰燃烧过程中其他燃烧中间产物和不同燃空比对CH_3单脉冲成像的影响,讨论了现有条件下该技术的应用范围。根据实验结果,在燃空比Φ=1.2的条件下,在反应区我们获得了信噪比约为8的单脉冲成像,分析火焰中CH_3的单脉冲成像结果可知火焰燃空比在1.0~1.4之间时,或者火焰中CH_3的浓度大于9.3×1015 molecules·cm-3信噪比较好。该项技术在动力机械及其他研究领域的应用有十分重要的参考价值。     

4,7-二(2-溴代噻吩-5-基)-2,1,3-苯并噻二唑-N-(1-辛基壬烷基)咔唑在ZnS(100)表面吸附的理论研究

采用密度泛函理论中的广义梯度近似(DFT/GGA)方法, 在PW91/DNP水平上研究了4,7-二(2-溴代噻吩-5-基)-2,1,3-苯并噻二唑-N-(1-辛基壬烷基)咔唑(简称PC-DTBT)的低聚合物(PC-DTBT)n(n=1-5)的稳定性和化学活性. 结果表明: 随着聚合度增加, (PC-DTBT)n的稳定性降低, 化学活性增强. 采用密度泛函理论与周期性平板模型相结合的方法, 研究了PC-DTBT单体在ZnS(100)表面的吸附, 通过吸附前后化合物PC-DTBT的Mulliken charge和前线轨道分析表明: 当PC-DTBT吸附在ZnS (100)表面时, ZnS(100)表面向PC-DTBT转移0.200 e电荷, 前线轨道能隙变窄. 理论预测的结果与实验值吻合.