痕量N2O气体检测系统的设计与实现

建立了基于光谱吸收技术的检测系统,用于快速、准确地测量N2O气体浓度。首先,从理论上证明了二次谐波、一次谐波与N2O气体浓度之间的关系;然后,设计了痕量N2O气体浓度检测系统,利用光源调制、锁相放大等技术,实现了强杂波背景下气体浓度弱信号的解析;最后,实验测试了系统的检测性能、抗干扰能力及检测结果的可重复性。测试结果表明,系统能够在0～1%有效检测N2O气体浓度,检测下限为5.0×10-5,相对检测误差为0.11%,检测结果线性方程为Y=192.699 09 X-0.006 24,线性度为0.998 07。多次检测实验表明,系统相对标准偏差为0.137%,CO2、O2、水蒸气等常见气体对检测结果无影响。改变激光器的中心波长,该方法亦可用于CO2,CH4等其它温室气体的检测。     

气体受激拉曼散射系统的分析与优化

为了优化气体受激拉曼散射系统,采用理论与实验相结合的方法,对气体受激拉曼散射现象进行了研究。根据受激拉曼基本理论计算了CH_4和D_2在不同气压下的拉曼增益系数,然后采用输出能量为70mJ的Nd∶YAG三倍频355nm激光进行了受激拉曼散射实验,测量了在拉曼池气体气压为1×105～2×10~6 Pa,焦距分别为500,750mm下的斯托克斯光的输出能量。发现CH_4拉曼增益系数随气体压力升高而增大;D_2拉曼增益系数在1×10~6 Pa左右达到最大值,之后不随气压升高而改变。实验结果表明,在气体受激拉曼装置中,合理选择拉曼池气体气压和耦合聚焦透镜的焦距,即甲烷气体系统选择长焦距高气压,氘气系统选择长焦距低气压。理论计算与实验结果基本一致,此研究对NO_2差分吸收激光雷达光源系统的优化有着很重要的作用。     

燃气泄露检测的CO-CH4气体变送器

以MSP430F149单片机为核心,研制了1台应用于燃气泄漏检测的CO-CH4气体变送器,实现对应CO气体0～200×10-6、CH4气体0～5 000×10-6的0～3 V线性电压输出,分辨率分别为20×10-6和500×10-6.详细叙述了气体传感器的采样时序产生电路,放大电路以及线性化模拟电压的输出方法.     

湿度和SF_6在石英增强光声光谱中对CO分子弛豫率的影响

为了研究六氟化硫(SF_6)气体分子和水汽(H_2O)对一氧化碳(CO)气体分子的弛豫率的影响,建立了一个基于石英增强光声光谱(QEPAS)技术的痕量气体传感器系统。采用1.57μm的近红外分布式反馈二极管激光器作为激励光源,并对不同SF_6和H_2O气体浓度下的CO的光声信号进行对比研究。首先用CO传感器系统探测CO与N_2的气体混合物中CO的光声信号,然后在CO与N_2气体混合物中加入不同浓度的SF_6气体,分别探测不同浓度SF_6气体下的CO光声信号强度。最后在CO与N_2的气体混合物中加入不同浓度H_2O,探测加入H_2O后的CO的光声信号强度。实验结果表明随着CO和N_2气体混合物中SF_6气体浓度的增加,CO的光声信号幅值几乎没有变化,而在混合物中加入2.5%的H_2O后,发现CO的光声信号提高了约5倍。因此,SF_6对CO气体的弛豫率没有明显的影响,然而H_2O的添加能够有效缩短CO气体的弛豫时间。     

采用100W功率溅射制备IWO薄膜特性研究

本实验用玻璃片作为基片,用纯度为99.99%的In2O3:W靶,其中In2O3:W质量比为98:2。调整系统背景真空度到1.7×10-3Pa,使用纯度为99.999%的高纯Ar气做工作气体用来起辉,工作气压为0.7Pa。采用100W功率,改变溅射时间制备IWO薄膜,以便得到溅射时间与薄膜光学电学特性变化之间的规律。     

真空紫外空阴极气体放电光源

真空紫外空阴极光源是一种稳定的气体放电光源,工作气体为He、Ne、Ar、N₂、H₂、CO等,工作气压10torr～10^-2torr,工作电流100mA～400mA,能在20～200nm波段产生丰富的原子和离子谱线,光谱辐射稳定性优于±1%。     

基于TDLAS技术的N_2O气体检测系统设计

基于红外光谱吸收及谐波检测原理,讨论了谐波信号和气体浓度关系,搭建了基于可调谐激光吸收光谱技术的气体检测系统。该系统采用低频锯齿波和高频正弦波联合调制激光器,并由锁相放大电路提取一次谐波和二次谐波信号幅值,以STM32F103VB控制器为核心,进行数据处理与数据上传,实现对0~0.1%浓度范围氧化亚氮(N_2O)气体实时测量。首先,介绍了系统的总体设计与核心结构,包括系统的硬件结构与软件结构;并进行了系统的标定和性能测试,结果表明二次谐波和一次谐波信号幅值比与浓度具有良好的线性关系,检测精度可达20×10~(-6),满足对N_2O气体实时监测的需求。     

基于光线追踪法的高精度CO2测量系统的研究

为了提高测量精度,对光线的有效利用率和最佳光程的选择进行了推导和优化。首先应用光线追踪法模拟CO2气室光路结构,计算光线的有效利用率;其次通过分析红外探测器接收到的光线,计算光程长对测量结果贡献率的影响,得出4.26μm波长下CO2的最佳光程为31mm。据此设计了CO2体积分数测量系统,并对20×10-6~1 500×10-6范围内的标准气体进行了测量。实验结果表明,该系统的测量精度可达到50×10-6。     

基于剩余幅度调制技术对强吸收下气体体积分数的测量研究

在可调谐半导体激光吸收光谱技术中,可利用剩余幅度调制信号实现对气体参数的免标定测量。然而现有RAM方法均需做弱吸收假设和简化,同时引入复杂的修正函数以提取完整的透射率信号用于气体浓度反演。针对此问题,建立了适用于任意吸光度和调制系数下的傅里叶光谱吸收模型,提出了直接对背景信号归一化的一次谐波Y分量进行拟合的免标定算法,减少了重建吸光度引入修正函数的过程。使用CH4为目标气体进行实验,体积分数计算的相对误差小于2%,标准偏差均小于4×10-2%,验证了该方法的可行性。     

风云三号红外高光谱探测仪的光谱定标

风云三号D星(FY-3D)于2017年11月15日成功发射,是我国第二代极轨气象卫星,其上搭载了红外高光谱大气探测仪(HIRAS),实现了地气系统的高光谱分辨率红外高精度观测,由于光谱频率的精确性会直接影响辐射精度,红外干涉仪器必须进行逐通道的光谱定标。首先对干涉图数据进行傅里叶变换获得粗定标结果,再基于仪器参数计算仪器线型函数,进行光谱精校正,开发了风云三号D星HIRAS的光谱定标技术,并用发射前和在轨数据进行了精度验证。光谱定标方法能有效订正由于仪器离轴探元设计引起的光谱位置偏差,基于地面单色激光测量数据验证,长波4个探元20×10~(-6)左右的偏差可订正到0.5×10~(-6)(1和2探元)和7×10~(-6)(3和4探元)以内;中波1四个探元50×10~(-6)左右的偏差可分别订正到6×10~(-6)(1和3探元)、8×10~(-6)(2探元)和13×10~(-6)(4探元)以内;基于在轨数据验证三个波段光谱订正后光谱精度偏差和标准差均可达到5×10~(-6)以内。三个波段光谱定标结果均满足卫星使用技术指标10×10~(-6)的要求,有效保证了辐射精度评估和后端遥感产品开发应用的要求。     

铬（Ⅵ）-鲁米诺-过氧化氢流动注射化学发光法测定对苯二酚

基于对苯二酚与铬（Ⅵ）的还原反应产生的铬（Ⅲ）催化鲁米诺-过氧化氢的化学发光,建立了一种快速测定对苯二酚的新方法。该方法线性范围为6.0×10-9～8.0×10-6 mol/L,检出限为1.0×10-10 mol/L。对1.5×10-6 mol/L扑热息痛平行测定8次,其标准偏差为3.1%。该法用于废水中对苯二酚含量的测定,结果令人满意。     

Note: response characteristics of the sensor based on LaF3 thin film to different humidified gases

Electromotive force (EMF) transient curves presented that the sensor showed good repeatable response in the humidity environments using ambient atmosphere as the carrier gas at different temperatures. The 90% response time and recovery time were within 40 s and 50 s, respectively. The sensor also presented stable response characteristics in 75.1% RH and 83.6% RH humidity environments using N(2), 5% O(2), and 50% O(2) as the carrier gases, respectively. The EMF always increased with the partial pressure of oxygen in certain relative humidity. However, the ΔEMF was decreased with the increase of O(2) content in the carrier gas under the condition of the variation of relative humidity from 75.1% to 83.6%. These phenomena revealed that the sensor was sensitive to water vapor without oxygen in the sample gas and too much water vapor had adverse effect on the response to oxygen. Non-Nernst behavior of the sensor was discussed in detail.     

分析温室气体及CO2碳同位素比值的傅里叶变换红外光谱仪

改进了傅里叶变换红外分析仪（FTIR）的硬件设计以实现温室气体及CO₂碳同位素比值的多组分、高精度、连续自动测量。首先,对FTIR分析仪测量系统进行了设计和理论分析,引入了温度和压力监控系统以及全密封气路干燥系统。然后,讨论了光谱的定量分析过程。最后,设计了标准气体对比测量实验。实验结果表明：分析仪测量CH₄,CO,CO₂和δ¹³CO₂值的标准偏差分别为0.01×10^-6,0.011×10^-6,0.239×10^-6和0.572‰,与常规FTIR测量系统相比,其检测的标准不确定度分别提高了6.3,8.45,10.54和14.73倍,其系统误差分别提高了2.88,1.93,4.67和4.66倍;对比分析仪与同位素质谱仪对δ¹³CO₂值的测量结果,标准偏差分别为0.572‰和0.171‰,二者测量的标准不确定度相近。所设计的温室气体及CO₂碳同位素比值FTIR分析仪能够满足多组分、高精度、连续自动测量的需要。     

Cryogenic EBSD on ice: preserving a stable surface in a low pressure SEM

Naturally deformed ice contains subgrains with characteristic geometries that have recently been identified in etched surfaces using high-resolution light microscopy (LM). The probable slip systems responsible for these subgrain boundary types can be determined using electron backscattered diffraction (EBSD), providing the etch features imaged with reflected LM can be retained during EBSD data acquisition in a scanning electron microscope (SEM). Retention of the etch features requires that the ice surface is stable. Depending on the pressure and temperature, sublimation of ice can occur. The equilibrium temperature for a low pressure SEM operating at 1 × 10(-6) hPa is about -112°C and operating at higher temperatures causes sublimation. Although charging of uncoated ice samples is reduced by sublimation, important information contained in the etch features are removed as the surface sublimes. We developed a method for collecting EBSD data on stable ice surfaces in a low pressure SEM. We found that operating at temperatures of <-112°C reduced sublimation so that the original etch surface features were retained. Charging, which occurred at low pressures (<1.5 × 10(-6) to 2.8 × 10(-5) hPa) was reduced by defocusing the beam. At very low pressures (<1.5 × 10(-6) hPa) the spatial resolution with a defocused beam at 10 kV was about 3 μm in the x-direction at -150°C and 0.5 μm at -120°C, because at higher temperature charging was less and only a small defocus was needed to compensate it. Angular resolution was better than 0.7° after orientation averaging. Excellent agreement was obtained between LM etch features and EBSD mapped microstructures. First results are shown, which indicate subgrain boundary types comprised of basal (tilt and twist) and nonbasal dislocations (tilt boundaries).     

RGA10质谱计的改进及在K-Ar、Ar-Ar同位素定年中的应用

对 RGA1 0质谱计离子源、分析室、样品提纯系统及数据处理系统等方面进行了改进 ,并增加了 3 8Ar大小球分取装置 ,使该仪器灵敏度、真空度及仪器的综合指标比过去有了较大改善 ,仪器的稳定性及测试样品的速度有了很大提高。仪器改造后三年来的实验证明 :Ar同位素的分析效率提高了 2至 3倍。     

超高功率体放电的形成及其应用

研究了氮气中的高压体(扩散)放电特性,实验中施加的极间隙脉冲电压达数百千伏,持续时间为数纳秒,上升时间为几个纳秒,给出了实验结果.研究了氦气压强为((0.4-2)×105Pa时,从扩散形式到火花放电的放电转换过程.确定了在氮气压强下电流幅度与逃逸电子束电流脉宽的关系.结果表明,导致隙间扩散放电的超短雪崩电子束(SAEB...     

球—盘摩擦试验初探

以2Cr12Ni4Mo3VNbN制成的Ф60×10的摩擦盘作为试验工件,通过球—盘摩擦试验这种新的刀具优选方法,研究YG6硬质合金球和纯Al2O3球对工件摩擦行为的影响,以此对刀具的设计、优化起到一定指导作用。     

Determination of polychlorinated dibenzo-p-dioxins,dibenzofurans, and biphenyls by gas chromatography/mass spectrometry in the negative chemical ionization mode with different reagent gases

Reagent gases that are used in mass spectrometry in the NCI mode for the determination of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) are discussed. Ion-molecule reactions and respective characteristic ions that form while using reagent gases (CH(4), O(2), i-C(4)H(10), NH(3), H(2), He, Ar, Xe, SF(6)) or gas mixtures (CH(4)/O(2), Ar/CH(4), CH(4)/H(2)O, Ar/O(2), i-C(4)H(10)/CH(2)Cl(2)/O(2)) are reviewed. It is shown that only CH(4), O(2), CH(4)/O(2), and CH(4)/N(2)O are widely used and well studied, even though-in the case of these reagent gases-there are contradictions between the publications of various authors. Such reagent gases as NH(3) and He are not well studied, but further investigations of their use for the determination of organochlorine pollutants could be of interest. The possibilities of more sensitive and selective determination of PCDDs, PCDFs, and PCBs are discussed.     

Development of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics for the free electron density of laser-generated plasma

This article reports on the development and set-up of a Nomarski-type multi-frame interferometer as a time and space resolving diagnostics of the free electron density in laser-generated plasma. The interferometer allows the recording of a series of 4 images within 6 ns of a single laser-plasma interaction. For the setup presented here, the minimal accessible free electron density is 5 × 10(18) cm(-3), the maximal one is 2 × 10(20) cm(-3). Furthermore, it provides a resolution of the electron density in space of 50 μm and in time of 0.5 ns for one image with a customizable magnification in space for each of the 4 images. The electron density was evaluated from the interferograms using an Abel inversion algorithm. The functionality of the system was proven during first experiments and the experimental results are presented and discussed. A ray tracing procedure was realized to verify the interferometry pictures taken. In particular, the experimental results are compared to simulations and show excellent agreement, providing a conclusive picture of the evolution of the electron density distribution.     

硫酸-H2O2-罗丹明B-体系阻抑动力学光度法测定痕量EDTA的研究

研究阻抑动力学光度法测定痕量EDTA的新体系。在硫酸介质中,Fe（Ⅲ）催化H2O2氧化罗丹明B的反应可被微量EDTA有效地阻抑,被过量EDTA有效的终止,据此建立了测定痕量EDTA的动力学光度法,用固定时间法在555 nm波长处监测阻抑反应。在0～45.0μg/50mL范围为,线性关系良好,回归方程为ΔA=2.25×10^-2c（c：μg/50mL）,γ=0.9991,检出限为1.1×1 0^-6mg/mL。该方法用于罐头等食品中EDTA的测定,获得满意结果。