Diffuse Reflectance Spectra of Some Nd3+ Complexes: Bonding

The absorption spectra of Na³⁺ complexes have been a subject of several recent investigations.^1–7 In the absorption spectra of solutions, the solvent effect makes it difficult to study the energy levels of the complexes. This difficulty can be overcome by studying the absorption spectra of single crystals or diffuse reflectance spectra of powders. Since the complexes under study do not form good single crystals, it was thought worthwhile to study their diffuse reflectance spectra, which have not been studied so far. The present communication reports a comparative study of bonding in six complexes inferred from their diffuse reflectance spectra.     

基于漫反射光谱的组织光学参数测量系统与方法研究

在体组织光学参数测量是生物医学光子学研究重点,不仅为人体成分无创检测、光学成像、光动力疗法等研究提供基础,并且可以快速获取人体光学参数变化,为临床诊断提供依据。研究了利用单一源探距离漫反射光谱在体测量光学参数的测量系统与反构方法。漫反射光谱测量系统由宽谱光源、高分辨光纤光谱仪及光纤探头组成,结构简单,测量方便,可准确快速测量样品漫反射光谱。在光纤探头几何形状基础上,研究了光纤收集及系统传递函数,在此基础上对反构算法进行了校正。光学参数反构算法中正向模型基于Monte Carlo以及神经网络方法,适用光学参数范围大,计算速度快;逆向算法采用主成分分析与非线性建模拟合相结合的方法,可抑制测量噪声影响。在测量系统及反构算法基础上,进行了组织仿体光学参数测量实验,结果表明,利用单一源探距离下漫反射谱,可以较为准确获取吸收系数以及约化散射系数,均方根误差分别达到4.58%以及7.92%。为保证系统测量准确性,测量波长范围应覆盖样品中所含吸收物质吸收峰范围。所研究的在体组织光学参数测量方法为人体成分无创检测及测量条件变化获取提供了基础。     

几种不同产地高岭土的漫反射傅里叶红外光谱分析

分别采用压片法与漫反射法测得几种不同产地高岭土的红外吸收谱图,解析了各高岭土的结构特征与吸收峰值的关系,发现利用漫反射傅里叶红外光谱技术,经K-M函数校正的红外谱图较压片法灵敏度高,也更准确,解析更简单;依据对高频区3700～3600cm-1波数段高岭石OH基特征吸收峰的吸收情况,可快速判断高岭石结晶度,结果与X射线衍射技术所测Hinckley指数(Hi)一致。     

(NaZSM-5)-AgI主体-客体纳米复合材料的研究

用热扩散法成功地把AgI组装于NaZSM5的孔道中,对制备的样品(NaZSM5)AgI进行了化学分析、粉末XRD分析、化学吸附、红外光谱表征,研究了所制备的样品固体扩散漫反射吸收光谱及发光性质.化学分析表明,AgI已进入NaZSM5主体中.粉末XRD分析显示了组装AgI后NaZSM5沸石骨架依然存在,红外光谱表明了(NaZSM5)AgI样品骨架振动与NaZSM5的骨架振动有细微差别,这主要是由组装了AgI引起的.吸附研究说明了AgI已进入NaZSM5的孔道.固体扩散漫反射吸收光谱表明,主体NaZSM5对制备的主体客体样品光吸收几乎没有影响,(NaZSM5)AgI的吸收光谱受AgI尺寸大小的影响.发光研究表明,制备的样品能带隙很高,辐射过程很强,(NaZSM5)AgI样品系具有发光功能的复合材料.     

Optical diffuse reflectance spectra of GaSb nanocrystals embedded in SiO2 matrix by radio-frequency magnetron co-sputtering

Nanocrystalline GaSb embedded in SiO₂ films was grown by radio-frequency magnetron co-sputtering. X-ray diffraction pattern and transmission electron microscopy (TEM) confirm the existence of GaSb nanocrystals in the SiO₂ matrix. The average size of GaSb nanoparticles is in the range of 3 to 11 nm. Diffuse reflectance spectra were used to characterize the small change of the band gap of the semiconductor. The diffuse reflectance spectra shows that the absorption peaks have a large blueshift of about 4.0 eV of the absorption relative to that of bulk GaSb. It has been explained by quantum confinement effects. Room temperature optical transmission spectra show that the absorption edge exhibits a very large blueshift of about 2.1 eV with respect to that of bulk GaSb in agreement with quantum confinement. Received: 28 July 1999 / Accepted: 27 October 1999 / Published online: 1 March 2000     

漫反射光谱用于光动力治疗中鲜红斑痣皮肤氧含量监测的初步研究

尝试利用漫反射光谱检测鲜红斑痣皮肤的氧含量,并用于监测光动力治疗中鲜红斑痣皮肤氧含量的变化。采用Ocean Optics公司生产的USB2000微型光纤光谱仪采集PWS皮肤的漫反射光谱,根据氧合血红蛋白与还原血红蛋白(皮肤中两种主要的吸光基团)吸收光谱的差异,分析病变皮肤氧含量及治疗中氧含量的变化趋势。对14例PWS患者进行治疗中皮肤漫反射光谱的监测。结果显示,治疗前不同类型PWS皮肤氧含量不同,光动力治疗中大部分P4、P5型PWS皮肤氧含量没有显著降低,P6型PWS皮肤氧含量降低明显。表明现有的漫反射光谱法可定性监测PWS皮肤氧含量的变化趋势。通过进一步提高仪器的灵敏度并建立相应的光谱分析方法,有望更准确地测量PWS皮肤中的氧含量变化。     

漫反射光谱技术对文物保护及相关问题的研究

应用自行研制的光导纤维反射分光光度计,研究了漫反射光谱技术在文物保护研究中的应用。主要工作包括： (1)通过比较待测颜料和标准颜料反射光谱曲线的形状和特征反射峰或一阶导数峰的位置,实现对彩绘文物颜料的分析鉴定。(2)用漫反射光谱技术监测金属表面状态的变化。文中通过对铜及其锈蚀产物漫反射光谱的研究得到了铜表面的一些信息,可见漫反射光谱技术对金属表面状态的研究具有特殊的功能。(3)通过研究文物保护修复材料的反射光谱特性,指导人们选择适宜的材料。作者的研究证实了漫反射光谱法是一种新的文物保护研究技术,具有简便、快捷和不损坏文物的特点,该工作使漫反射光谱技术成为文物保护研究的一种新的检测手段,同时也为漫反射光谱分析开辟了新的研究应用领域。     

三维漫射光谱法检测猪肉嫩度的初步研究

猪肉是光的强散射物质,嫩度是评价猪肉品质优劣的重要标准之一,提出一种基于三维漫射光谱法的猪肉嫩度检测方式。将猪肉样本更多的散射信息引入光谱分析中。利用实验室搭建的数据采集系统,通过采集距光源入射点不同距离处的样本漫反射光信号构建了64个猪肉样本的三维漫射光谱。经过小波消噪处理后,利用多维偏最小二乘法(NPLS)建立了三维漫射光谱与猪肉嫩度之间的分析模型,模型的校正决定系数R2_Cal是0.883 1,校正标准差RMSEC是3.685 0N,预测决定系数R2_Pred是0.874 7,预测标准差RMSEP是3.9756N。实验结果表明, 与常规的漫反射光谱法相比,三维漫射光谱法所建立的猪肉嫩度NPLS模型具有更高的校正精度和预测稳健性,有望为猪肉嫩度及其他品质的快速检测提供一种新的途径。     

Quantitative UV-Visible Diffuse Reflectance Spectroscopy of Solid Powders

In spite of difficulties in attaining high resolution, the determination of UV-VIS-NIR spectra via diffuse reflectance spectro-scopic measurements on solid powders; provides several advantages. Compounds which are difficult to obtain as suitable single crystals, or are found to be unstable or insoluble in liquid solution, can only be studied by diffuse reflectance spectroscopy. Also, since no solvents are required, any effects due to solvation are eliminated. However, it is not possible to resolve the observed spectrum into its anisotropic components, as in the case of single crystal spectra.     

不同含水量黑土土壤光谱反射率半经验模型构建

土壤含水量的变化情况与时空分布对热量平衡、农业墒情等具有显著的影响。利用反射率光谱信息反演土壤含水量的研究,可为实现土壤含水量速测、揭示土壤含水量时空变异规律提供科学依据。构建不同含水量黑土土壤反射率光谱半经验模型,深入探究土壤重量含水量与反射率光谱的关系。 制备了12种不同湿度的土壤样品。 采用ASD Field Spec Pro 3地物波谱仪对制备的不同湿度梯度的黑土土壤进行反射率光谱测量。 利用菲涅耳反射率建立土壤表面反射模型;在以往的研究中,Kubelka-Munk (KM)模型中的漫反射率R_∞通常被视为对于给定材料和照明波长的常数或需要反演的参数。通过研究发现,漫反射率R_∞不仅与材料和波长有关,还与土壤含水量相关。利用与土壤含水量相关的吸收系数及散射系数描述了土壤含水量与漫反射率R_∞的关系,并基于KM理论对体散射分量进行建模;进而构建不同含水量黑土土壤反射率光谱半经验模型。 根据实际测量数据选用最小二乘算法对模型参数进行反演,并通过分析反演参数简化模型。最后,将未参与建模的不同含水量梯度的数据代入模型中,验证模型的有效性。结果表明：对比不同含水量土壤反射率光谱的模拟值与实测值在400～2 400 nm波段范围内的模拟精度发现,含水量为200 g·kg-1的土壤反射率光谱的均方根误差最大,为0.008,含水量为40 g·kg-1的土壤反射率光谱的均方根误差最小,为0.000 6,不同含水量下土壤样品反射率光谱的均方根误差的均值是0.005 1。在400～2 400 nm波段范围内,不同波长下黑土土壤反射率光谱的预测均方根误差基本低于0.008,1 920 nm波长处的预测均方根误差最小,为0.002 062。采集长春地区的土壤检验模型的可靠性,配制15个不同含水量样品并对其进行反射率光谱测量。选取9个样品数据用于建模,6个样品数据用于验证。结果表明：在400～2 400 nm波段范围内,不同波长下的长春土壤反射率光谱的预测均方根误差基本低于0.015,525 nm波长处的预测均方根误差最小,为0.000 922 5。综上所述,所建立的模型具有很高的预测精度,可很好地适用于不同含水量黑土土壤反射率光谱的模拟。     

采用氧合血红蛋白吸收带的漫反射光谱比率R540/R575检测人胃癌

采用氧合血红蛋白吸收带的平均漫反射光谱比率(R540/R575)对离体的人正常胃、未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮粘膜组织进行鉴别诊断.实验采用带积分球附件的分光光度计测量组织样品在400 nm～600 nm的漫反射光谱.实验结果表明,在相同的波长范围内,人的未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮粘膜组织的漫反射光的强度较人正常胃的上皮粘膜组织的漫反射光强度要显著地低的,尤其是在氧合血红蛋白的吸收带540 nm和575 nm波长处,人正常胃、未分化胃腺癌、胃鳞状细胞癌和低分化胃腺癌的上皮粘膜组织的平均漫反射光谱比率分别是(94.25±2.4)%,(109±3.0)%,(1032±2.8)%和(98.6±2.6)%.     

Determination of human skin optical properties in vivo from reflectance spectroscopic measurements

A novel approach has been proved to quickly and non-invasively determine the optical properties of human skin in vivo. It is based on the diffuse reflectance approximation model and subjected to the well established library of absorption spectra of water and hemoglobin. Under the nonlinear least-square algorithm, fitting the measured spectra in the range of 400-1000 nm to the diffusion approximation model, the reduced scattering coefficient and absorption coefficient of skin tissue can be quickly determined in vivo. The results show that this method is convenient and suitable for the real-time clinical application.     

Diffuse Reflectance Spectrum of Ferric Oxide

The spectra of many complexes of Fe³⁺ have been reported in literature. The absorption, in thin films⁵ of ferric oxide has also been studied. The diffuse reflectance spectrum of pure ferric oxide powder down to only 300 mμ has been published by Vratny and Kokalas⁶ but the bands were neither well marked nor interpreted. No such studies below 300 mμ have been reported. The present communication extends the region of study of the diffuse reflectance spectra of both pure and diluted samples of ferric oxide up to 200 mμ.     

二维相关光谱分析在无创血糖检测特异性研究中的应用

主要利用二维相关光谱分析方法考察了血液中主要成分、测量过程中的系统漂移等因素对近红外光谱中的葡萄糖分子特异性的影响。首先测量了葡萄糖水溶液的近红外透射光谱,以葡萄糖浓度为外扰,计算二维相关同步谱及异步谱,通过对比分析确定了葡萄糖在合频和倍频区域的特征吸收峰位置。当葡萄糖水溶液中加入少量白蛋白后,其二维相关谱中葡萄糖的一级倍频吸收峰(1 590 nm)和二级倍频吸收峰(1 195 nm)出现了不同源的现象,表明白蛋白可能破坏了葡萄糖的特异性;进一步开展了人体口服葡萄糖耐量实验,测量了手掌部位的漫反射光谱,其二维相关谱中葡萄糖的同源性吸收也遭到破坏。另外,由于葡萄糖浓度变化引起的光谱变异信息较小,很容易被系统漂移掩盖,一般需要进行背景修正。在葡萄糖水溶液的透射实验和人体漫反射实验中,分别引入纯水样本和5%标准漫反射板作为参考,以时间为扰动的二维相关光谱分析的结果表明,经过参考样本的背景校正后,系统漂移在二维同步切线谱中引起的谱峰偏移变小,葡萄糖的特征吸收被增强。因此,在近红外光谱无创血糖检测中,应尽量避开与葡萄糖特征吸收不同源的波段,并有必要采取一定的参考测量方法以提高检测的特异性。     

A new semiconducting organic-inorganic nanocomposite, 1,5-diaminonphthalene-saponite intercalation compound

We synthesized a new intercalation compound, 1,5-diaminonaphathalene(DAN)-saponite where intercalated DAN molecules were shown to have a formal charge of +0.67 The measurement of optical diffuse reflectance spectra revealed the formation of electronic bands with a gap of ca. 1 eV suggesting semiconducting behaviour of this system. From ESR measurements, the radical formation in DAN-saponite was confirmed and the spin concentration was determined to be 1 spin per 200 and 300 DAN-molecules at 290 and 7.9 K, respectively. This temperature dependence of the spin density also implies the semiconductive nature of DAN-saponite.     

基于近红外漫反射与漫透射光谱的玉米单倍体鉴别比较研究

使用JDSU公司的MicroNIR1700型微型近红外光谱仪,研究了适合进行单籽粒玉米单倍体鉴别的光谱测量方法。基于近红外光谱定性分析技术,比较了漫反射和漫透射两种情况下玉米单倍体鉴别的效果。光谱数据经过预处理后,采用PLS＋OLDA特征提取算法,应用SVM建立玉米单倍体鉴别模型,分别统计漫反射和漫透射实验条件下,鉴别模型的正确识别率。在微型光谱仪内置光源漫反射的光谱测量方式下,不分胚面朝向,玉米单倍体籽粒平均识别率低于60%,不能有效鉴别玉米单倍体和多倍体。而采用外置光源对籽粒进行漫透射光谱测量方式,获得了平均正确识别率为93.2%的鉴别效果,并且模型稳定性好。实验结果表明,漫反射光谱仅能获得玉米籽粒表层信息,因此玉米籽粒胚面朝向严重影响漫反射光谱鉴别单倍体种子的效果;而漫透射光谱可以实现分析光程纵深信息全累加,能够得到样品内部的信息,因此对胚面朝向不敏感,能够有效地对随机摆放的玉米单倍体和多倍体进行识别。近红外方法能快速、无损地鉴别单倍体,并且微型光谱仪采集速度快,成本低,为实现实用化的自动鉴别提供了条件。     

有机和无机国画颜料漫反射光谱和吸收光谱特征研究

国画颜料解混一直是古画颜料研究的重要内容,其中光纤反射光谱（FORS）是无损化探测颜料类别的常用手段。通过CCD光纤光谱系统,从光谱线型对国画颜料进行了分类,分别探测了两种有机植物颜料藤黄和胭脂在不同比例混合下的漫反射光谱与吸收光谱,并获取了不同色系无机矿物质颜料混合后的漫反射光谱。分析了单一颜料和混合颜料的光谱特征峰值,运用多元线性回归（MLR）以及一阶导数光谱法（FDS）,通过全波段线性解混获得了各组分颜料的比例。经过实验与理论分析,藤黄与胭脂的漫反射光谱为S型,混合颜料一阶导数光谱中两特征峰的位置分别为536和649 nm,在漫反射光谱中多元线性回归基本适用于该混合颜料的解混并显示出一定的线性规律,但无法精确地解混。而混合颜料的吸收光谱与单色光谱之间存在较好的线性关系,解混误差在5%左右。无机矿物质颜料中的漫反射光谱有S型（石黄和赭石）和钟型（石青和石绿）两种。首先,对于S型（石黄）与S型（赭石）混合颜料漫反射光谱,赭石的一阶导数光谱出现明显的“三峰”现象,并且混合颜料一阶导数光谱在534 nm处出现新的特征峰。多元线性回归理论虽适用于该混合颜料的解混,但由于不同颜料解混的权重因子不同,无法形成较为精准的线性模型。其次,对于S型（赭石）与钟型（石绿）混合颜料的反射光谱需要多元线性回归与导数光谱法共同判断混合比例的基本趋势,该光谱在400～800 nm范围内仅有一个交叉点。最后,利用钟型（石青）与钟型（石绿）混合颜料反射光谱的特征峰位置,即可判断出颜料混合比例的特征,随着混合比例的变化,反射光谱特征峰在457～524 nm出现了明显的横向移动,并且混合颜料光谱的峰值强度有明显的减弱。     

Diffuse reflectance of TiO2 pigmented paints: Spectral dependence of the average pathlength parameter and the forward scattering ratio

Diffuse reflectance spectra of paint coatings with different pigment concentrations, normally illuminated with unpolarized radiation, have been measured. A four-flux radiative transfer approach is used to model the diffuse reflectance of TiO₂ (rutile) pigmented coatings through the solar spectral range. The spectral dependence of the average pathlength parameter and of the forward scattering ratio for diffuse radiation, are explicitly incorporated into this four-flux model from two novel approximations. The size distribution of the pigments has been taken into account to obtain the averages of the four-flux parameters: scattering and absorption cross sections, forward scattering ratios for collimated and isotropic diffuse radiation, and coefficients involved in the expansion of the single particle phase function in terms of Legendre polynomials.     

Optical properties of the subcutaneous adipose tissue in the spectral range 400–2500 nm

The optical characteristics of subcutaneous adipose tissue are studied in the wavelength range 400–2500 nm. The experiments are conducted in vitro using a Cary 2415 spectrophotometer. Based on the measured diffuse reflectance and total transmittance spectra, the spectra of the absorption and transport scattering coefficients are calculated in terms of the inverse adding-doubling method.     

Characterization of Cds clusters in zeolite-A grown in alkaline solution

CdS clusters were synthesized in A type zeolite by reaction in alkaline aqueous solution at temperatures from 30 to 70 °C. The optical properties of the samples were studied by diffuse reflectance and photoluminescence spectroscopy. Their crystalline structure and morphology were studied by X-ray diffraction and by transmission and scanning electron microscopy. We found that at lower temperatures the CdS clusters are encapsulated in the zeolite cages. We compared the properties of these clusters with those encapsulated in the cages of zeolites X and Y, prepared by similar methods. CdS clusters smaller than the CdS exciton diameter are also formed outside the cages in the zeolite matrix. The size of these clusters increases with temperature producing a red-shift of the absorption edge in the optical absorption spectra.