近玻尔速度Ne2+离子穿过碳膜引起的电子发射

本文测量了入射能为2–25 keV/u的Ne²⁺离子穿过不同厚度碳膜诱导的前向、后向 (分别对应出射表面和入射表面) 电子发射产额. 实验中通过改变炮弹离子的能量, 系统的研究了势能沉积、电子能损以及反冲原子对前向、后向电子发射产额的贡献. 结果表明, 离子的势能沉积只对后向电子发射有贡献, 前向、后向电子发射产额分别与Ne²⁺离子在薄膜出射、入射表面的电子能损近似成正比关系, 其中电子能损很低 (对应于离子能量很低) 的时候, 反冲原子对电子发射的贡献不能忽略. 关键词： 近玻尔速度 电子发射 电子能损 反冲原子     

室温生长ZnO薄膜晶体管的紫外响应特性

在室温下采用射频磁控溅射法制备了以ZnO薄膜为沟道层的薄膜晶体管(TFTs).研究表明ZnO薄膜在紫外区具有较高的吸收率,并且ZnO-TFTs对紫外光照射较为敏感.因此,进一步深入研究了ZnO-TFTs紫外光照下的输出和转移特性,结果表明,紫外光照将引起较为明显的光响应电流,且经过光照的器件在光源移除7天后,ZnO沟道层中仍能观察到残余电导现象,其原因可以归结为紫外光辐射在ZnO沟道层中引入了一定数量的氧空位施主态缺陷.     

水溶性CdTe:Mn量子点的双光子吸收

采用激发波长800 nm、脉宽50 fs、重复频率1 kHz的Ti:sapphire放大飞秒激光器作为激发光源,利用开孔Z扫描技术研究了不同粒径的CdTe:Mn量子点的非线性吸收性质。理论计算结果表明,同一生长时间CdTe:Mn量子点的双光子吸收系数是CdTe量子点的1.1倍,其双光子吸收系数随量子点尺寸的减小而增大,这是由于CdTe:Mn量子点非线性吸收属于反饱和吸收,掺杂了Mn元素,减小了表面缺陷浓度,表明掺杂量子点具有很好的双光子吸收现象。     

基于可调谐半导体激光吸收光谱技术的逃逸氨在线监测研究

可调谐半导体激光吸收光谱技术(TDLAS)具有高选择性、高准确性的优点,为逃逸氨的在线检测提供了可靠的技术手段。首先研究了温度对NH3浓度检测的影响,表明在25³00℃之间,浓度随温度的升高而降低;然后在室温为25℃时,利用TDLAS系统对浓度为10300℃之间,浓度随温度的升高而降低;然后在室温为25℃时,利用TDLAS系统对浓度为10¹00ppm的NH3进行检测,采集得到其二次谐波光谱。比较了单光程和多光程样品池测量结果,得到单光程样品池最低检出限为22.9ppm,多光程样品池的检测限为1.21ppm,多光程样品池能够明显地提高检测精度。结果表明,该系统能够适应现场测量环境。     

黄芩素稳定性研究

用紫外光谱研究了光、温度、pH、Na2SO3、FeSO4及抗坏血酸对黄芩素稳定性的影响.在室温条件下,黄芩素溶液的吸光度值在6h内强度有明显的下降;当温度升高或在避光条件下,偏酸性黄芩素溶液的吸光度值在6h内强度不变,而碱性条件下依然有下降趋势;但黄芩素溶液加入抗坏血酸或Na2SO3后,吸光度值可稳定不变.本文研究提示:黄芩素对光和pH稳定性差;抗坏血酸和Na2SO3具有提高黄芩素溶液稳定性的作用.     

Determination of optical constants in DUV/VUV

An approach for determining the optical constants of the weakly absorbing substrate is developed and applied to obtain the parameters of CaF2 and fused silica substrates in deep ultraviolet （DUV） and vacuum ultraviolet （VUV） range. A method for extracting the optical constants of thin films deposited on strongly absorbing substrate, which is based on the reflectance spectra measured at different angles of incidence, is also presented. The optical constants are determined by fitting the measured spectra to the theoretical models. The proposed method is applied to determine the refractive index and extinction coefficient （n, k） of MgF2 film deposited on silicon substrate by electron beam evaporation with substrate temperature 300 ℃ and deposition rate 0.2 nm/s. The determined n, k values at 193 nm are 1.433 and 9.1×10-4, respectively.     

Improving attosecond pulse reflection by large angle incidence for a periodic multilayer mirror in the extreme ultraviolet region

The improvement of attosecond pulse reflection by large angle incidence for a periodic multilayer mirror in the extreme ultraviolet region has been discussed. Numerical simulations of both spectral and temporal reflection characteristics of periodic multilayer mirrors under various incident angles have been analyzed and compared. It was found that the periodic multilayer mirror under a larger incidence angle can provide not only higher integrated reflectivity but also a broader reflection band with negligible dispersion, making it possible to obtain better a reflected pulse that has a higher pulse reflection efficiency and shorter pulse duration for attosecond pulse reflection. In addition, by increasing the incident angle, the promotion of attosecond pulse reflection capability has been proven for periodic multilayer mirrors with arbitrary layers.     

Extraction and verification of coherent structures in near-wall turbulence

According to the characteristics of coherent structures in near-wall turbulence, an accurate extraction and verification method is developed based on wavelet transform (WT) and correlation analysis in this paper. At first, the fluid field of a turbulent boundary layer is measured precisely in a gravitational low-speed water tunnel. On the basis of the distribution of the coherent structures, velocity data of three test points are selected and analyzed, whose dimensionless heights are 20.8, 33.5, and 42.6. According to the frequency range of power spectrum density (PSD), coherent and incoherent structures are both extracted from the original signals using continuous and orthogonal wavelet transforms. To confirm the validity of the extracted signals, the probability density function (PDF) of each extracted signal is calculated. The result demonstrates that the incoherent structures obey the Gaussian distribution, while the coherent structures deviate from the Gaussian distribution. The PDFs of the coherent structures and the original signals are similar, which shows that the coherent structures make most contributions to the turbulence. For further verification, a correlation parameter between coherent and incoherent structures is defined, which evidently proves the validity of the extraction method in this paper.     

超高数值孔径Schwarzschild投影光刻物镜的光学设计

针对45nm及以下节点光刻相关技术的研究需求,确定了实验型投影光刻物镜的结构型式及设计指标。依据像差理论在非同心小遮拦的Schwarzschild反射系统中添加折射补偿镜组来进一步减小系统的中心遮拦,扩大像方数值孔径。设计了一套小中心遮拦,数值孔径为1.20的Schwarzschild折反式投影光刻物镜。设计结果表明,该投影光刻物镜工作带宽为100pm,像方视场为50μm,线中心遮拦比为13%,光学分辨力为80nm时(6240lp/mm)的系统调制传递函数大于0.45,全视场最大畸变为6.5nm,满足了45nm深紫外(DUV)浸没光刻实验平台对投影光刻物镜的需求。     

空间高层大气遥感远紫外成像光谱仪的光学系统

空间高层大气遥感远紫外成像光谱仪主要用于观测高层大气中的远紫外辐射和实现对其内部中尺度现象成像的功能。目前我国该类的相关仪器研究基础还比较薄弱,针对这种情况,在光学系统设计的角度上给出了一种适用于130～180nm波段探测的光学系统方案。该成像光谱仪光学系统以离轴抛物镜为物镜,串联Wadsworth结构为成像光谱系统;这种串联Wadsworth成像光谱系统采用离轴抛物镜做准直镜,分光器件为平面光栅和球面光栅串联,实现二次色散,同时球面光栅起到聚焦成像作用;在像差理论的基础上,对该结构的光程函数和各像差进行了分析,获得了改进结构的宽波段完善成像条件。针对低轨空间探测应用要求设计了相关改进型Wadsworth结构成像光谱仪光学系统,设计结果证明系统像差得到了充分校正,在奈奎斯特频率(20lp/mm)下全视场全波段调制传递函数值在0.6以上。该优化结构同时具备高空间分辨率和高光谱分辨率,性能优越。