Multiplexed reflective-matched optical fiber grating interrogation technique

The multiplexed-reflective matched fiber grating interrogation technique was presented in this paper. The interrogation technique was based on the use of two (or more) wavelength-matched fiber Bragg gratings (FBGs) to receive the reflected signal from the sensing FBG. The two (or more) matched gratings were arranged parallelly and used as filters to convert wavelength into intensity encoded information for interrogation. Theoretical and experimental results demonstrated that the interrogation system is immune to the source fluctuation and cross-sensitivity effect between temperature and strain, and also can enlarge the dynamic range.     

脉冲偏压占空比对多孔氧化硅薄膜性质的影响

采用由脉冲负偏压调节的等离子体增强化学气相沉积方法,以硅烷为源气体,在玻璃基片上沉积得到了多孔二氧化硅薄膜。将反应过程中加在沉积区域的脉冲偏压固定在-350V,当占空比从0.162增大到0.864时,薄膜样品的形貌、成份和结构均不相同。扫描电镜照片表明,组成多孔氧化硅薄膜的颗粒在占空比增大时变得细腻,并且薄膜整体变得多孔且蓬松。拉曼光谱和红外光谱结果显示,薄膜样品中的非晶硅和Si-H键在较高的占空比下减弱甚至消失。占空比升高时氧化硅桥键所占比例持续增加。     

ASYMMETRY PARAMETERS AND DIFFERENTIAL CROSS SECTIONS FOR PHOTOIONIZATION-EXCITATION OF HELIUM

Asymmetry parameter β₂ for photoionization of helium leaving the He⁺ ion in the n=2 level and differential cross sections(DCSs) in the n=2,3,4 levels with photon emission angle θ=90⁰ are provided at photon energies 69-76.8 eV employing the R-matrix method with a 20-term target representation, in which five polarization orbitals \bar{6}l are included. The asymmetry parameter β₂ and the DCS, in the n=2 level in the region of 69-73 eV, are in good agreement with available experimental and theoretical results. Above the n=3 threshold, we present new theoretical results along with measurements. No theoretical and experimental results can be used to compare with the present calculations of the DCSs for photoionization into the He⁺ ion in the n=3,4 levels.     

ASYMMETRY PARAMETERS AND DIFFERENTIAL CROSSSECTIONS FOR PHOTOIONIZATION-EXCITATION OF HELIUM

Asymmetry parameterβ2 for photoionization of helium leaving the He+ ion in the n = 2 level and differential cross sections(DCSs) in the n = 2, 3, 4 levels with photon emission angle θ=90°are provided at photon energies 69－76.8 eV employing the R-matrix method with a 20-term target representation, in which five polarization orbitals 6l are included. The asymmetry parameter β2 and the DCS, in the n=2 level in the region of 69－73eV, are in good agreement with available experimental and theoretical results. Above the n = 3 threshold, we present new theoretical results along with measurements. No theoretical and experimental results can be used to compare with the present calculations of the DCSs for photoionization into the He+ ion in the n = 3, 4 levels.     

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采用由脉冲负偏压调节的等离子体增强化学气相沉积方法,以硅烷为源气体,在玻璃基片上沉积得到了多孔二氧化硅薄膜。将反应过程中加在沉积区域的脉冲偏压固定在-350V,当占空比从0.162增大到0.864时,薄膜样品的形貌、成份和结构均不相同。扫描电镜照片表明,组成多孔氧化硅薄膜的颗粒在占空比增大时变得细腻,并且薄膜整体变得多孔且蓬松。拉曼光谱和红外光谱结果显示,薄膜样品中的非晶硅和Si-H键在较高的占空比下减弱甚至消失。占空比升高时氧化硅桥键所占比例持续增加。     

多孔氧化硅薄膜阴极射线谱的研究

采用近常压下等离子体增强化学气相沉积的方法制备得到多孔氧化硅薄膜,并在沉积区域加载偏压对薄膜形貌和性质进行调制。扫描电镜显示偏压条件下沉积的薄膜更加蓬松多孔,常温下阴极射线谱表明:增大偏压的占空比,CL谱中发光峰的位置并不改变,但谱线强度增大。发光峰的位置说明薄膜中的主要成分是Si-O-Si基团,且该种基团以非桥键的形式存在,薄膜中还存在少量的Si-H键,这与红外光谱测试结果一致。X射线衍射结果表明薄膜中的SiO2是非晶态的。     

介质阻挡放电等离子体沉积多孔硅纳米颗粒膜的光发射及红外光谱

用介质阻挡放电(DBD)等离子体增强化学气相沉积(PECVD)的方法,以硅烷为源气体,在沉积区域加载脉冲负偏压进行调节,在玻璃基片上沉积得到具有荧光特征的多孔硅纳米颗粒膜。沉积过程的发射光谱结果表明,在412 nm处出现S iH*(A2Δ→X2Π0-0)特征峰,证明放电沉积过程中存在不同程度的硅烷裂解。将脉冲负偏压固定在-300 V,当占空比从0.162增大到0.864时,薄膜的红外光谱显示S i—O—S i在1 070cm-1伸缩振动吸收峰与800 cm-1的弯曲振动峰都有所增强,而930 cm-1的S i—H弯曲振动减弱。说明随着占空比的增加,S i—O—S i键的结合越来越明显。     

大学物理中关于光的干涉、衍射及光栅教学问题的讨论

从三个实验现象出发，详细讨论了三个实验图样的特点，明暗纹分布规律以及定量计算公式的推导，并对这三部分的教学顺序提出了建议．     

圆极化激光场中e-He散射

把二级玻恩近似(SBA)的方法推广至圆极化激光场,计算了发生多光子交换时的激光辅助电子被氦原子散射的微分散射截面。对计算结果进行了分析,并与线性极化激光辅助散射结果进行了比较。     

多场耦合非热平衡低温等离子体与微纳米结构材料的相互作用

低温等离子体是制备微纳米材料和调控其结构特性的最重要方法之一,其中材料结构及特性的改变是等离子体电磁场、热场、化学场等多场耦合综合作用的结果.本文系统而简要地回顾了如下主要内容:电源的频率及其调制、施加方式对等离子体放电特性与稳定性的影响;大气压等离子体物理化学反应动力学;等离子体场对微纳米颗粒的聚集态结构与运动的调控、以及对沉积薄膜微纳米结构的影响.总结并得出如下主要结论:放电频率、脉冲调制功率、容性或者感性耦合方式、单体种类、基片温度等对等离子体活性粒子成分与特性具有主要影响,在kHz～MHz范围可以实现稳定放电和微纳米颗粒制备和薄膜沉积;微纳米颗粒/颗粒膜结构形貌随时间和空间而发生动态变化;低温等离子体多场调制可以快速实现微纳米颗粒的结晶,并调控微纳米颗粒的成分、尺度、带隙、晶型、晶面比例及其形貌特征;引入微颗粒可以在鞘层位置悬浮形成规则的二维等离子体晶格与无序的等离子体非晶,在介观尺度研究复杂系统的结构与动理学过程.