几种加氢裂化催化剂的太赫兹光谱研究

采用太赫兹时域光谱(THz-TDS)方法,本文研究了几种Y型加氢裂化催化剂(NaY、ReY、USY和HY)在0.2-1.2THz频段的光谱特性.与此同时,对其中的NaY分子筛进行了加热处理,测量了其经过不同温度处理后的太赫兹时域光谱.通过快速傅里叶变换,分别得到了不同种类和不同温度处理后催化剂的太赫兹吸收谱和折射率谱.研究结果表明,太赫兹时域光谱技术既能用于催化剂的种类鉴别和性能表征,又能给出不同温度下催化剂本身内部结构变化对应的太赫兹光谱响应.本研究工作的展开,证明了太赫兹方法用于催化剂性质表征的可行性,对太赫兹技术在催化领域的应用具有一定的指导意义.     

环氧树脂及其混合物的太赫兹光谱分析

本文采用太赫兹时域光谱（THz-TDS）技术研究了四种不同环氧值的环氧树脂在0.2～2.6 THz波段的光学性能和光谱特性,并通过计算获得了四种树脂的吸收系数和折射率。同时,基于四种环氧树脂的吸收谱,本文还对三种按不同质量百分数混合的环氧树脂混合物的太赫兹吸收光谱进行分析。实验结果显示,四种环氧树脂在太赫兹频率范围内没有明显的吸收峰,但各个样品吸收曲线和折射率曲线有显著的差异。运用最小二乘拟合的方法对混合物的吸收谱进行拟合,拟合得到的混合物吸收谱与实验所得的结果相符合。因此,根据太赫兹光谱包含的特征信息能够对混合物进行分析,证实了太赫兹波谱技术将在定量分析领域具有潜在的应用前景。     

原油超声处理的太赫兹时域光谱分析

基于太赫兹时域光谱技术研究了经过超声处理的两种原油在0.1～1.4 THz波段的光学性质,得到了样品的吸收谱和折射率谱发现经过不同时间超声作用的原油,其太赫兹光谱曲线变化显著,说明样品的结构组成分子在能级共振位置上,均出现了不同的吸收和折射特性.太赫兹时域光谱可作为波形分析技术为原油超声处理时超声强度、频率、作用时间等参数的选择提供理论依据.     

低温条件下汽车发动机润滑油的太赫兹时域光谱研究

采用太赫兹时域光谱技术研究润滑油的低温性能。在自建的透射式太赫兹时域光谱系统上,检测几种润滑油在-40~0 ℃间的太赫兹时域谱,并通过对太赫兹时域谱的处理得到润滑油的吸收系数和折射率。结果表明,低温导致润滑油中烃类物质结晶析出,使得润滑油黏度增大并且丧失流动性;温度降低对润滑油的影响在太赫兹时域光谱图中表现为时间延迟增大,温度与时间延迟表现出一定规律性;温度降低导致润滑油折射率增大,吸收系数增大,折射率与温度变化也呈现出相关性。研究证明太赫兹时域光谱技术能十分有效地检测温度变化对润滑油的影响,可用于研究润滑油的低温性能。     

基于太赫兹时域光谱的汽车发动机油低温性能研究

采用太赫兹时域光谱技术研究润滑油的低温性能。在自建的透射式太赫兹时域光谱系统上,检测几种润滑油在-40~0℃间的太赫兹时域谱,并通过对太赫兹时域谱的处理得到润滑油的吸收系数和折射率。结果表明,低温导致润滑油中烃类物质结晶析出,使得润滑油黏度增大并且丧失流动性;温度降低对润滑油的影响在太赫兹时域光谱图中表现为时间延迟增大,温度与时间延迟表现出一定规律性;温度降低导致润滑油折射率增大,吸收系数增大,折射率与温度变化也呈现出相关性。研究证明太赫兹时域光谱技术能十分有效地检测温度变化对润滑油的影响,可用于研究润滑油的低温性能。     

用太赫兹时域光谱技术对防虫防蛀剂进行质量检测

太赫兹时域光谱技术可以分辨化合物结构上的微小差异并应用于物质检测与分析,为有机化工产品的鉴别及更宽有效光谱区的测试提供了新的实验方法。本文运用太赫兹时域光谱技术研究了樟脑、对二氯苯和萘三种防虫防蛀剂在太赫兹波段的光学特性。在室温氮气环境中,得到了樟脑、对二氟笨和萘在0．2-2．5THz波段的折射率和吸收谱,样品在此波段的折射率和吸收谱存在显著差异。对二氟苯和萘都有毒性。实验表明,用太赫兹时域光谱技术可以清楚地分辨出三种防虫防蛀剂以及其混合物的折射率和吸收谱的差异,通过判断特征谱线的差异从而判断此种防虫防蛀剂的毒性,此法简单,快速,准确。     

三种橡胶材料的太赫兹光谱研究

本文利用太赫兹时域光谱技术研究了氯丁橡胶、丁腈橡胶和三元乙丙橡胶在0.2～1.8 THz频段的光学性能和光谱特性,得到了三种橡胶的时域谱、折射率谱和吸收谱,进而计算橡胶在0.2～1.8 THz频段的吸收系数和折射率,结果表明可以通过吸收系数与折射率来区分不同种类的橡胶。这种方法为认识橡胶对太赫兹波的响应机制提供了科学依据,有望为橡胶材料鉴别提供一种有效的分析手段。     

原油中硫含量的太赫兹时域光谱检测

原油中硫含量的快速检测对于原油的安全生产、运输、加工和环境保护均具有十分重要的意义.本文运用太赫兹时域光谱技术对不同硫含量的原油进行了实验测量,经过计算得到了样品的吸收谱和折射率谱.通过对这些光谱进行分析,结果表明太赫兹时域光谱不仅能够有效的检测出原油中的硫含量,还能实现对原油中物质的溶解程度进行定性的预测.     

基于太赫兹光谱技术的抗生素类药物检测研究

本文利用太赫兹时域光谱技术在室温下对几种在临床和人们日常生活中常用的抗生素类药物阿莫西林、青霉素钠、头孢氢氨苄和头孢拉丁进行了光谱测量,获得了四种物质在0.2-1.7THz波段的吸收谱和折射谱,发现这四种抗生素类药物在太赫兹波段均存在明显的特征吸收峰,可作为其在太赫兹波段的指纹谱用于药物分子识别。本研究表明,太赫兹时域光谱技术在常用抗生素类药物的物质鉴别及药品质量检查方面有着广泛的应用前景。     

双层样本中界面对太赫兹时域光谱的影响研究

针对多层样本中界面对太赫兹时域光谱的影响问题,利用太赫兹时域光谱测试了由不同粒径制成的单、双层沙粒压片,获得了单、双层压片样本的太赫兹时域谱。结果表明,双层样本的单位厚度太赫兹峰值衰减系数明显小于单层样本的单位厚度衰减系数。因此,在研究双层样品太赫兹光谱响应时应添加某个系数以消除由样品的界面反射影响,且该系数与材料的特性有关。     

A Setup for Investigating Induced Refractive Index Change in Optical Fibers at High Temperatures

An automated experimental setup for investigating the mechanisms of refractive index change in optical fibers at high temperatures is described. A resistive furnace that allows a section of an optical fiber to be heated from room temperature to 1200°C at a given rate was developed. The results from experiments on annealing gratings formed in a germanosilicate fiber with 14 mol % GeO₂ in the fiber core are presented. The temperature stability of photoinduced fiber refractive index gratings at different demarcation energies was calculated on the basis of the data obtained.__________Translated from Pribory i Tekhnika Eksperimenta, No. 4, 2005, pp. 76–83.Original Russian Text Copyright © 2005 by Bozhkov, Vasil’ev, Medvedkov, Grekov, Korolev.     

基于太赫兹光谱的天冬氨酸结构分析及鉴定

太赫兹时域光谱技术（THz-TDS）是一种新的远红外波段光谱测量技术,对化合物结构上的微小差异变化十分敏感,因此成为物质分析与检测的新型方法。文章基于太赫兹时域光谱技术的测定方法,在氮气环境中考察不同来源天冬氨酸在太赫兹波段的吸收特性,并结合差示扫描量热仪（DSC）和傅立叶变换红外光谱仪（FITR）进一步验证THz测定结果的有效性。实验结果表明,用太赫兹时域光谱技术可以清楚地分辨出不同结构天冬氨酸的差异,方法简单,快速,准确。     

玻璃封装医用小型光纤光栅温度传感探头

针对体内测温、特别是肿瘤热疗体内温度实时监测对温度传感探头的体积、韧性和抗电磁干扰能力的要求,对医用小型光纤光栅温度传感探头进行了研究。提出了利用玻璃管封装短光纤布拉格光栅来有效避免应力引起的误差以及金属封装对电磁场分布的影响,同时提出用医用聚氨酯套管包裹探头及光纤来有效地保护探头及光纤并使其具备很好的韧性。封装后,探头截面直径为1mm、长度约为4mm。实验测量了稳定温度源在不同温度下探头的反射波长响应和温度变化时探头的响应时间,并测量了医用热疗机加热猪肉时肉内部的温度变化过程。结果表明,体温范围内探头反射波长与温度的线性相关系数可达0.999 95,温度传感精度为0.2℃,探头最大响应时间约为4s,并能实时监测医用热疗机加热猪肉时其内部的温度变化。     

太赫兹技术对营养品中蛋白质含量的研究

采用太赫兹时域光谱(THz-TDS)和红外光谱分析技术,研究了3种奶粉、杏仁粉和白砂糖的光学性能和光谱特性。通过对比样品在1658 cm-1和1747 cm-1处的红外光谱吸收峰,可以判定蛋白质和脂肪含量的差别。对比样品在THz波段的吸收系数和折射率,蛋白质含量较高的样品其吸收系数和折射率较高。观察样品的红外吸收峰强度和位置难以定量分析样品的蛋白质含量,但可以利用样品在THz波段的吸收系数与折射率有效地判定营养品中蛋白质的含量。实验结果表明蛋白质在太赫兹波段比在红外波段有更好的区分性,THz-TDS技术有望为营养品中蛋白质含量检测提供一种有效的分析手段。     

固化剂及其固化物的太赫兹光谱分析

太赫兹时域光谱技术可以分辨化合物结构上的微小差异并应用于物质检测与分析,为物质的鉴别及更宽有效光谱区的测试提供了新的实验方法。本文采用太赫兹时域光谱（THz-TDS）技术,在室温氮气环境下对固化剂及其固化产物进行了光谱测试,获得了样品在0.2-2.5THz波段的时域光谱,并通过计算得到固化剂及其固化物的吸收谱及折射率谱。实验结果表明,固化剂和固化物在THz范围内敏感,可以根据各自在THz波段的特征光谱得以区分。     

High sensitivity all-fiber Sagnac interferometer temperature sensor using a selective ethanol-filled photonic crystal fiber

An all-fiber Sagnac temperature sensor based on 3?dB tapered coupling and ethanol selective-filled photonic crystal fiber was demonstrated theoretically and experimentally. The ethanol selectivity-filled photonic crystal fiber has noncircular symmetry and thus exhibits birefringence. The ethanol selective-filled photonic crystal fiber, acting as the sensing element, was inserted in a Sagnac loop interferometer to measure temperature. The output spectra of Sagnac interferometer applied different temperatures were measured and analyzed. Experimental results have shown the temperature sensitivity of the Sagnac interferometer is 1.65?nm/°C in the range of 25–33°C.     

In situ synthesis of carbon nanotubes on heated scanning probes using dip pen techniques

Carbon nanotubes (CNT) were synthesized on heated scanning probes and under ambient conditions without requiring Chemical vapor deposition (CVD) apparatus or process gases. In this study, dip pen nanolithography (DPN) techniques were utilized for deposition of catalyst precursors on the scanning probe tips in the form of aqueous solution of metal salts--prior to the synthesis of the CNT. A layer of fullerene (C(60)) of approximately 200 nm thickness was vapor deposited on the scanning probe tip prior to the deposition of the metal catalyst. During the in situ synthesis of the CNT on the scanning probes, the temperature of the heated scanning probes reached 350-400 degrees C. Hence the scanning probes were heated in an inert atmosphere to prevent potential oxidation of the deposited fullerene layer. The synthesized CNTs were subsequently characterized using SEM and Raman spectroscopy. The Raman spectroscopy showed peaks in the Radial breathing mode (RBM), as well as the defect (D) and graphitic (G) bands. The RBM peaks indicate that the single walled carbon nanotube (SWCNT) ranged in diameter from 0.9-1.5 nm. The peaks in the Raman spectra are indicative of SWCNT mixtures (metallic and semconducting) and possibly multiwalled carbon nanotube (MWCNT). Hence this process can be optimized to synthesize SWCNT of a specific chirality (metallic or semiconducting). This study differs from an earlier study reported in the literature involving synthesis of CNT on scanning probes where the process temperatures typically exceeded 700 degrees C, and resulted in synthesis of highly graphitic MWCNT (Sunden, et al., 2006).     

Flash heating in the diamond cell: melting curve of rhenium

A new method for measuring melting temperatures in the laser-heated diamond cell is described. This method circumvents previous problems associated with the sample instability, thermal runaway, and chemical reactions. Samples were heated with a single, 20 milliseconds rectangular pulse from a fiber laser, monitoring their thermal response with a fast photomultiplier while measuring the steady state temperature with a CCD spectrometer. The samples were recovered and analyzed using scanning electron microscopy. Focused ion beam milling allowed to examine both the lateral and the vertical solid-liquid boundaries. Ambient pressure tests reproducibly yielded the known melting temperatures of rhenium and molybdenum. Melting of Re was measured to 50 GPa, a 5-fold extension of previous data. The refractory character of Re is drastically enhanced by pressure, in contrast to Mo.     

Effect of thermal properties on laser cutting of continuous glass and carbon fiber-reinforced polyamide 6 composites

The single mode fiber laser cutting of two types of continuous fiber-reinforced thermoplastic composites (TPC) with polyamide 6 (PA6) matrix and a fiber content of 60 wt% was investigated: a glass fiber-reinforced composite (PA6/GF60) and a carbon fiber-reinforced composite (PA6/CF60). Preliminary, the thermal properties of the composites were analyzed to derive the cutting mechanisms. Thermogravimetric Analysis (TGA) showed decomposition onset temperatures of 457.6°C for the PA6 matrix and 737.3°C for the carbon fibers, while no thermal decomposition of the glass fibers was detected up to 1,000°C. In consequence, the single mode fiber laser cutting of the PA6/GF60 composites required a significantly higher number of cutting cycles in conjunction with an increased heat affected zone (HAZ) as compared to the PA6/CF60 composites. Analysis of the HAZ and the mechanical properties of the laser cut composites by optical microscopy and uniaxial tensile testing showed an anisotropy and dependency on the laminate structure. However, the obtained mechanical properties of the laser cut composites were found comparable to their water jet cut counterparts.