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1.
王杨  谢品华  李昂  曾议  徐晋  司福祺 《物理学报》2012,61(11):114209-114209
直射太阳光差分吸收光谱技术(DS-DOAS)近 年来成功应用于大气痕量气体的垂直柱浓度测量. 本文研究了基于被动DOAS算法可用于连续测量NO2整层垂直柱浓度的DS-DOAS技术, 介绍了测量系统的构成.利用统计最小值外推法减少了由参考谱引入的误差.分析了测量结果的误差来源, 估算了误差大小.报道了该系统在合肥地区对NO2进行的连续11天的测量, 分析了测量结 果.通过实验验证了算法的可行性, 证实了该技术可实现连续测量NO2整层垂直柱浓度.  相似文献   

2.
利用壳层模型分子动力学方法,考虑萤石结构分子中的预熔化现象,对SrF2和BaF2的分子动力学模拟熔化温度进行修正,获得了高压下SrF2和BaF2的熔化温度. 同时给出了300 K、0.1 Mpa~7GPa和0.1 Mpa~3 GPa时SrF2和BaF2的状态方程,与已有研究结果的最大误差分别为0.3%和2.2%. 计算所得SrF2和BaF2常压下的熔点与已有的实验结果符合较好. 对于SrF2和BaF2分子体积变化和已有的熔化模拟的差别也做了比较和讨论.  相似文献   

3.
本文采用发射光谱法诊断了大气压下Ar气、SiCl4及H2气混合气体(Ar/SiCl4/H2)射频放电等离子体射流特性.利用Si原子谱线强度计算了电子激发温度并以此估算了Si原子数密度,研究了射频功率及气体流量对电子激发温度和Si原子数密度以及SiCl4解离率的作用.  相似文献   

4.
黄海  陆艳艳  王文杰 《物理学报》2012,61(16):167401-167401
根据两带Ginzburg-Landau 理论计算了层状超导材料NbS2的上临界磁场, 以及上临界磁场各向异性参数随温度的变化情况, 并将NbS2与MgB2, NbSe2上临界磁场的各向异性进行比较. 所得计算结果与已有实验数据符合得很好, 充分说明了NbS2的超导电性具有两能隙特征. NbS2上临界磁场各向异性参数在5.0 K附近逐渐变小, 这与MgB2和NbSe2有相似之处. 但NbS2的上临界磁场各向异性参数大约为7.3, 明显大于MgB2和NbSe2. 计算结果还表明, NbS2较大能隙所对应能带的有效质量比约为54, 另一能带的有效质量基本为各向同性.  相似文献   

5.
 基于不同波长的光闪烁,采用修正的大气湍流Hill谱模型,提出了一种同时反演大气湍流内尺度及折射率结构常数的方法。假定内尺度在某一个范围内取值,对于不同波长的闪烁指数,如果当内尺度取某一定值时,由光传输理论计算的C2n1,…)和C2n (λ2,…)相等,反演成功。根据此原理设计了三波长闪烁计并在某地进行了外场测量。近地面大气湍流的内尺度一般在2~10 mm之间,且随折射率结构常数(其量级为10-16~10-13)的变化而变化,两者之间存在一定的正相关;任意两波长组合进行反演得到的内尺度(或折射率结构常数)值具有自洽性,其相关系数的最小值为0.81,因此证明了该方法的可行性。  相似文献   

6.
在Mg(IO3)2-H2O体系中发现了一个新的物相二水碘酸镁Mg(IO3)2·2H2O.用称重法测定了Mg(IO3)2,Mg(IO3)2·2H2O和Mg(IO2)2·4H2O的溶解度随温度变化的曲线。  相似文献   

7.
对新合成的化合物氯化苯并咪唑镧HCl4·[C7H6N2(H2O)2]2La及其LaCl3·5H2O的水溶液进行了三维荧光光谱测定,讨论了HCl4·[C7H6N2(H2O)2]2La在不同波长的光激发下的荧光特性,荧光强度与浓度的关系及标题化合物的上转换荧光,即在540nm绿光的激发下可以获得紫外光(290nm)和近紫外光(360nm).  相似文献   

8.
邹帅  唐中华  吉亮亮  苏晓东  辛煜 《物理学报》2012,61(7):75204-075204
本文首先利用悬浮型微波共振探针测量了Ar等离子体的电子密度,并与朗缪尔双探针的测量结果进行了比较,表明了微波共振探针在低密度等离子体测量的可行性.对40.68 MHz单射频容性耦合Ar/SF6和SF6/O2等离子体的测量结果表明:电负性气体SF6掺入Ar等离子体显著降低了等离子体电子密度,但随着增加SF6的流量,电子密度表现为缓慢下降;而O2掺入SF6等离子体中,电子密度则随着O2流量的增加表现为持续的下降.另外,40.68 MHz/13.56 MHz双频激发的SF6/O2容性耦合离子体的电子密度并不随低频功率的变化而变化.本文对上述的实验现象进行了初步的解释.  相似文献   

9.
李万万  孙康 《物理学报》2007,56(11):6514-6520
将生长得到的Cd0.9Zn0.1Te晶体在Cd气氛下及不同的温度条件下进行了退火处理. 借助已建立的退火处理过程中Cd1-xZnxTe晶体材料电阻率及导电类型变化和扩散杂质的扩散系数之间关系的模型,结合实验数据,获得了1073K,973K和873K下Cd在Cd0.9Zn0.1Te晶体中的扩散系数,并估算了其激活能. 通过使用获得的扩散系数,研究了在不同温度及饱和Cd气氛下,退火时间对Cd0.9Zn0.1Te晶体电阻率分布及导电类型等的变化的影响.  相似文献   

10.
LBO晶体上1 064,532 nm倍频增透膜的镀制及性能分析   总被引:4,自引:1,他引:4       下载免费PDF全文
 用电子束蒸发沉积方法在X切LBO(X-LBO)晶体上镀制了两种不同膜系结构的1 064和532 nm倍频增透膜,其中一种膜系结构为基底/ZrO2/Y2O3/Al2O3/SiO2/空气,另一种为基底/0.5Al2O3/ZrO2/Y2O3/Al2O3/SiO2/空气,两种膜系结构的主要差别在于有无氧化铝过渡层。测量了薄膜的反射率光谱曲线,发现两种增透膜在1 064和532 nm处的反射率均小于0.5%,实际镀制结果与理论设计曲线的差异主要是由材料折射率的变化引起的。且对样品在空气环境中进行了温度为473 K的退火处理,结果发现两种膜系结构均表现了较优异的光学性能,氧化铝过渡层的加入使薄膜具有强的热应力性能。  相似文献   

11.
The Rare Isotope Science Project (RISP) is launched in Korea to build the IF and ISOL facilities. Current status of RISP is introduced.  相似文献   

12.
The applicability of laser processing for small-lot micro-electromechanical system devices is discussed in this paper. This simple process could replace conventional complex processes designed with mass production in mind. Ablation, protrusions or surface modification is revealed to occur by argon ion laser scanning into silicon. Which of them occurs depends on the laser power. It is found that the protrusions are covered by a thin layer of oxide; however, oxidation of the modified surface is not established even though some results suggest it. Surface modification is more applicable to surface patterning than coarse protrusion is because the laser-modified surface can be used as a mask in KOH etching to make sharp patterns. The applicability of this method is indicated by demonstrating pattern width control, patterning over a large area and the fabrication of a 16-bit linear scale.  相似文献   

13.
A high-resolution particle image velocimetry was used to characterize a low Reynolds number turbulent flow in a channel. Experiments were conducted over a sand grain-coated surface of large relative roughness, and the results were compared with measurements over a smooth surface. The roughness perturbation significantly modified the outer layer. Even though the streamwise Reynolds stress shows less sensitivity in the outer layer to the boundary condition, significant enhancements were observed in the wall-normal Reynolds stress and the Reynolds shear stress. These modifications were considered as footprints of the larger-scale eddies transporting intense wall-normal motions away from the rough wall. A quadrant decomposition shows that strong and more frequent ejections are responsible for the larger values of the mean Reynolds shear stress over the rough wall. The results also indicate that spanwise vortex cores with mean vorticity of the same sign as the mean shear are the dominant smaller-scale vortical structures over the smooth and rough walls. A linear stochastic estimation-based analysis shows that the average larger-scale structure associated with these vortices is a shear layer that strongly connects the outer layer flow to the near-wall flow. A proper orthogonal decomposition of the flow suggests that the large-scale eddy is more energetic for the rough wall, and contributes more significantly to the resolved turbulent kinetic energy and the Reynolds shear stress than the smooth wall.  相似文献   

14.
Hierarchical zinc oxide (ZnO) micro/nanostructured thin films were grown onto as-prepared and different annealed ZnO seed layer films by a simple two step chemical process. A cost effective successive ionic layer adsorption and reaction (SILAR) method was employed to grow the seed layer films at optimal temperature (80 °C) and secondly, different hierarchical based ZnO structured thin films were deposited over the seed layered films by chemical bath deposition (CBD). The influence of seed layer on the structural, surface morphological, optical and wettability behavior of the ZnO thin films were systematically investigated. The XRD analysis confirms the high crystalline nature of both the seed layer and corresponding ZnO micro/nanostructured films with a perfect hexagonal structure oriented along (0 0 2) direction. The surface morphology revels a complex and orientated hierarchical based ZnO structured films with diverse shapes from plates to hexagonal rod-like crystal to tube-like structure and even much more complex needle-like shapes during secondary nucleation, by changing the seed layer conditions. The water contact angle (WCA) measurements on hierarchical ZnO structured films are completely examined to study its surface wettability behavior for its suitability in future self-cleaning application. Photoluminescence (PL) spectra of the ZnO structured film exhibit UV and visible emissions in the range of 420-500 nm. The present approach demonstrates its potential for low-temperature, large-scale, controlled synthesis of crystalline hierarchical ZnO nanostructures films.  相似文献   

15.
The distribution of oxygen present in the surface layer of the Si-sphere used as new mass standard is measured and quantified using the combined X-ray fluorescence (XRF)/X-ray photoelectron spectroscopy (XPS) surface analysis system in the Center for Measurement Standards, Industrial Technology Research Institute (CMS/ITRI). A radiometric calibration of the X-ray source is not possible because the spectral distribution of the X-ray tube used is complex and not stable over the long term. Hence, the quantification of oxygen on the Si-sphere is based on a calibration curve that establishes a correlation between the mass deposition of oxygen from the calibration samples qualified by PTB and the ratio of the oxygen fluorescence to silicon RRS (resonant Raman scattering) intensities in the in-house system. This paper presents the methodology for and the results of an oxygen quantification performed using the combined XRF/XPS surface analysis system. With a relative uncertainty of less than 10%, the average mass deposition of oxygen on the Si-sphere was 133 ± 12 ng/cm2. The oxygen quantified via XRF is treated as a reference for the quantification of other elements on the surface layer. The quantification of carbon mass deposition in the surface layer in relation to the oxygen mass deposition is also described in this paper. The surface analysis system is part of our contribution to the realization and dissemination of the unit of the kilogram (based on its new definition) via the XRCD method.  相似文献   

16.
 利用强流脉冲(HCPEB)电子束技术,对AISI 304L奥氏体不锈钢进行了辐照处理,并利用透射电子显微镜对HCPEB诱发的空位簇缺陷进行了表征。实验结果表明,HCPEB辐照金属可在辐照表层诱发大量的过饱和空位,并形成空位型位错圈和堆垛层错四面体(SFT)。利用金相显微镜、扫描电子显微镜和非接触式光学轮廓仪,对其表面形貌进行了详细的表征,发现电子束处理后的样品表面形成了高密度、弥散分布和尺寸细小的微孔,表面微孔是由于HCPEB轰击诱发的大量空位(簇)缺陷,以线或面等结构缺陷为路径,向表层迁移导致空位的累积而形成的。采用HCPEB技术,选择合适的材料和辐照工艺参数,可以成功地制备出表面多孔金属材料。  相似文献   

17.
The high-resolution X-ray diffractometry (HRXRD) technique is known as a powerful tool for analyzing epitaxial heterostructures. However, standard analysis procedures do not allow the layer growth time to be used as a fixed parameter during HRXRD spectra analysis. The growth time in modern facilities is measured with a high degree of accuracy, which increases the reliability of HRXRD analysis particularly in the case of spectra with reduced quality or complex heterostructures consisting of a large number of individual homogeneous layers. A new algorithm is based on using flow rates of deposited components as variable parameters, while the layer growth times are taken as fixed parameters. A particular feature of this new approach is associated with the fact that the known growth time for each heterostructure layer is directly included into the algorithm for adjustment of the calculated spectrum to the experimental X-ray diffraction spectrum (HRXRD). The flows of deposited layers are variable parameters and, thus, the algorithm turned out to be very efficient for calibrating flow controllers in epitaxial growth reactors. The algorithm allows for reliable estimation of the flow even in the case of poorly informative HRXRD spectra.  相似文献   

18.
The formation of self-assembled monolayer and multilayer using redox-active Ru complex molecules with phosphonic acids on SiO2 surface has been examined using X-ray photoelectron spectroscopy (XPS), ellipsometry, and time of flight secondary mass-ion spectroscopy (TOF-SIMS). We found that an introduction of a Zr adlayer leads to higher surface molecular density of Ru complex SAMs on the SiO2 surface, compared to that of obtained from the direct adsorption of Ru complex monolayer on the SiO2 surface. We further tried to fabricate a multilayer film using this molecule with Zr(IV) ion acting as a chemical glue by a successive immersion process. The XPS data revealed that the molecular densities of the multilayers were also higher for the immobilization with Zr adlayer between Ru complex and SiO2 surface than those without the Zr adlayer, suggesting that Zr adlayer is effective in forming highly packed molecular layer of phosphonic acids on SiO2 surface. We found the film growth reached a saturation point after 6 layers on the SiO2 surface. The film growth saturation can be explained by a molecular domain boundary effect encountered due to the large tilt angle of the molecular layer.  相似文献   

19.
Cobalt chromium (Co-Cr) alloys have been widely used in the biomedical arena for cardiovascular, orthopedic and dental applications. Surface modification of the alloy allows us to tailor the interfacial properties to address critical challenges of Co-Cr alloy in medical applications. Self assembled monolayers (SAMs) of Octadecylphosphonic acid (ODPA) have been used to form thin films on the oxide layer of the Co-Cr alloy surface by solution deposition technique. The SAMs formed were investigated for their stability to oxidative conditions of ambient laboratory environment over periods of 1, 3, 7 and 14 days. The samples were then characterized for their stability using X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and contact angle measurements. Detailed high energy XPS elemental scans confirmed the presence of the phosphonic monolayer after oxidative exposure which suggested that the SAMs were firmly attached to the oxide layer of Co-Cr alloy. AFM images gave topographical data of the surface and showed islands of SAMs on Co-Cr alloy surface, before and after SAM formation and also over the duration of the oxidative exposure. Contact angle measurements confirmed the hydrophobicity of the surface over 14 days. Thus the SAMs were found to be stable for the duration of the study. These SAMs could be subsequently tailored by modifying the terminal functional groups and could be used for various potential biomedical applications such as drug delivery, biocompatibility and tissue integration.  相似文献   

20.
为了获取北极冰下声源方位信息,在北极冰层上方布放检波器和冰下投放声弹声源开展了冰下声源的分频段方位估计实验。研究结果表明,冰下声源方位估计的误差、准确率与检波器接收信号频段(或冰下声源信号频段)有关。采用低频段的接收信号进行方位估计时准确率较高,误差均值较小,所用接收信号频段≤250 Hz时,方位估计准确率可达72.9%;反之,采用高频段的接收信号进行方位估计时准确率低,误差均值较大。采用不同频段接收信号进行冰下声源方位估计时,误差大小与该站位相同频段内的反射系数的变化有关:反射系数变化较大时,误差较大;否则,误差较小。   相似文献   

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