臭氧标准参考光度计间接比对技术

参照国际计量局有关臭氧标准参考光度计(Standard Reference Photometer,SRP)间接比对的操作规程和美国环境保护署有关臭氧参考光度计之间比对验证的规定,采用臭氧传递标准,通过比对前的准备、比对过程的确定、比对结果的处理、比对指标的评价等步骤,开展了臭氧标准参考光度计间接比对实验。以SRPⅠ与SRPⅡ间接比对为例,SRPⅠ与SRPⅡ间接比对所得两个关系式的斜率分别为1.003 26和1.003 58,截距分别为0.109 05 nmol/mol和0.080 99 nmol/mol,结果显示两台SRP之间具有很好的一致性,比对结果符合美国环境保护署关于SRP之间比对的指标。建立了臭氧标准参考光度计之间的比对方法,适用于环境空气臭氧量值传递源头间的比对。     

Nearly-analogue blazed phase grating using high birefringence liquid crystal

Diffraction of liquid crystal gratings has been thoroughly studied for many applications such as diffraction optics, optical processing, and spectral analysis. In pure optical processing one varies the direction of propagation of light beam without any mechanical adjustment. In this work we propose a beam steering device using highly birefringent liquid crystal material. Using a highly birefringent material one can reduce the LC layer thickness needed to achieve 2π of phase modulation and thus reduce the fringing effect caused by deformation of the electric field at the edge of the pixel. Here, we present 1.5-μm thick, high-resolution diffraction grating with non-detectable fringing.     

可见到近红外波段整层大气光谱透过率的测量研究

利用太阳光谱辐射计进行了可见到近红外波段整层大气连续光谱透过率的测量研究.在对太阳辐射计可靠定标的条件下,通过测量太阳直射光谱,运用Langley方法推算到达大气层顶的太阳辐射,最终获得了该波段范围内的连续大气光谱透过率及特殊波长上的透过率的实际变化情况.通过分析晴天无云大气条件下不同时间、不同气溶胶含量、不同季节、不同气溶胶模式下的大气透过率特征,初步获得了其变化规律,为大气层外目标探测提供了一些基础.     

用LED灯和乐高积木实现Fe(Ⅲ)的定量测定*

在普通化学实验中引入以LED灯作为单色光源,用乐高积木和简单电子元件搭建简易光度计的教学环节。自制光度计采用2种方法搭建,结构简单,光路直观,成本低廉。将其用于Fe(Ⅲ)的定量测定,测试结果与商用光度计的测试结果进行比较,验证了自制光度计的性能。结果表明,在测试浓度范围内,吸光度与Fe(Ⅲ)浓度具有良好的线性拟合关系,测试结果满足基本的实验教学需求,可替代该实验中惯用的商用分光光度计。教学实践表明,这种自己搭建仪器并用于定量测定的教学模式,易于激发学生的学习兴趣与热情,增强学生的动手能力、独立思考和解决实际问题的能力,改善了教学效果。     

Micropumping multicommutation turbidimetric analysis of waters

A micropumping multicommutation manifold to perform turbidity determinations in waters is described. The procedure is based on the use of a combination of hydrazine sulfate and hexamethylenetetramine, to obtain an external standard of nephelometric turbidity units (NTU), which could compare the absorbance measurements at high wavelengths for samples with a calibration line obtained from a concentrated formazine standard diluted on-line. To minimize sample and reagent consumption and waste generation, the flow system was designed with two solenoid micro-pumps, one of them for the alternative introduction of the formazine standard and samples and the other one for the water carrier. The multicommutation approach makes possible the on-line dilution of a single standard to obtain the external calibration. The linear response was ranged up to 160 NTU. The coefficient of variation was estimated as 1.6 and 3.2% for 10 and 100 mm flow cell, respectively, for solutions containing 40 NTU (n = 10). Approximately, 60 determinations can be carried out per hour with limit of detection values of 1 and 0.1 NTU, consuming only 160 or 240 μL formazine solution and generating 1.8 or 2.0 mL waste per determination, using measurement cells of 10 and 100 mm optical pathlength, respectively. The procedure was successfully applied to 11 different water samples. Recovery studies were carried out and results obtained were between 97.5 ± 0.2 and 100 ± 1%. The development of a homebuilt light emitting diode (LED)-based portable flow analysis instrument was checked for in situ turbidimetric measurements, providing this equipment a LOD value of 0.09 NTU working with a blue LED at 464 nm and a LOD value of 0.1 NTU working with an IR LED.     

HG-AFS法测定甲鱼肉中硒

采用湿法消解原子荧光光度法对甲鱼肉中硒元素含量进行了分析测定。该方法加标回收率为96.2％～103.0％,相对标准偏差(RSD)为3.69％,猪肉国家标准物质(GBW08552)的测定值与标准值相吻合。结果表明： 甲鱼肉中硒元素的含量非常丰富,硒含量是普通动物鲜肉中的1.2～9.4倍;是新鲜瓜果蔬菜的几十至几百倍。本测定结果可为研制开发富硒甲鱼保健食品提供有价值的和可靠的科学依据。     

乙酸铵浸提原子吸收光谱法同时测定土壤交换性盐基离子组成

采用乙酸铵浸提,研究了利用原子吸收光谱法(AAS)同时测定土壤交换性Ca,Mg,K,Na的方法。结果表明,AAS法测定交换性盐基离子组成的准确度符合参比标准的要求;66个供试土样交换性Ca和Mg平行样品相对误差分别为0.02%～3.14%和0.06%～4.06%,平均相对误差分别为1.22%和1.25%。AAS法和火焰光度法(FP)测定交换性K和Na相对误差值分别为0.06%～8.93%和0.06%～1.54%,平均相对误差分别为3.72%和0.56%。实例研究结果表明AAS同时测定土壤交换性盐基离子组成方法可靠,可真实反映农田土壤交换性能的状况。     

AO3D: A Monte Carlo code for modeling of environmental light propagation

A Monte Carlo radiative transfer program (Atmosphere-Ocean 3-Dimensional, AO3D) for modeling the coupled atmosphere-ocean environment has been developed. The code allows for the specification of optical properties for the atmosphere, land and ocean. Light rays are tracked as they pass between the atmosphere and the ocean, reflect off the ocean surface, the ocean floor, and off land, or are absorbed. In this version the polarization of light rays is not considered. The optical properties of each horizontally homogeneous layer within the atmosphere and ocean can be set on a layer-by-layer basis with a choice of phase functions, absorption and scattering coefficients, and index of refraction. A wind-dependent Cox and Munk ocean surface realization (with whitecaps) is implemented to model refraction and reflection from surface waves. Either spherical- or flat-Earth models can be used, and all refraction and reflection are accounted for. The AO3D model has been tested by parts, and as a whole by comparison with single- and total-scattering calculations from other radiative transfer codes. Comparisons with Monte Carlo calculations by Adams and Kattawar (agreement in TOA radiance within the published precision ∼2%), MODTRAN4 (agreement in spherical-shell atmosphere (SSA) sky radiance within about 2%) and Coupled DIScrete Ordinate Radiative Transfer (COART) (agreement in plane-parallel (PP) sky radiance within 2%) are shown. Sun photometer measurements (including large air mass values) at the Mauna Loa Observatory are compared to AO3D simulations (for a spherical Earth) and suggest that a thin aerosol layer was present above the observatory at the time of the measurements.     

Structure and properties of macromolecules in shearflow

A laser light-scattering photometer is presented, the construction of which is based on the principle of a searle-type viscosimeter. It permits registration of the wideangle distribution of the scattered light in an area of 1 sr around the direction of the negative velocity gradient with high resolution (49 · 10^–6 sr).In the investigated range (0–3000 s^–1) the scope of shear-induced intensity changes of diluted solutions of polystyrene in benzene is 0.5–5 %. The alignment, control and measurement of several influencing factors, e. g. the positional and intensity stability of the primary beam, required a relatively high degree of performance.The relation of the intensity changes of the scattered and transmitted light are measured and illustrated as a function of shear cycles. In this way it is possible to recognize both the orientation and the deformation as well as the relaxation of shear-stressed PS-molecules. The discussion of the curves is guided by a simple instructional preview.     

根据太阳辐射反演沙尘粒子光学厚度个案分析

本文利用邱金桓提出的根据总直接太阳辐射反演0.75微米的气溶胶光学厚度的方法,以2002年3月20日至3月22日发生在我国的沙尘天气为例,使用中国气象局国家卫星气象中心提供的总直接太阳辐射观测资料,以三个观测站点:阿克苏、吐鲁番和福山为例,反演沙尘粒子光学厚度的日变化,并进行了对比检验。结果表明同一地点一天中早晚沙尘粒子光学厚度较小,中午较大;不同地点的沙尘粒子光学厚度随着该地点离沙尘源头的远近而不同,当距离越近时,沙尘粒子光学厚度的值也就越大,反之则越小,这与沙尘粒子迁移性的特点相适应。