一种新型平板彩色显示器件的制备和光谱分析

以MEH-PPV(聚[2-甲氧基-5-(2′-乙基己氧基-对苯乙烯)])和Alq₃作为发光层, 成功制备出ITO/SiO₂/MEH-PPV/SiO₂/Al结构和ITO/SiO₂/Alq₃ /SiO₂/Al结构的固态阴极射线器件。通过分析SSCL光谱,认为这些高速电子激发有机材料后形成Frenkel激子。当器件两个电极之间加的电压比较低时,有机薄膜层的场强也比较低,这些激子被解离的概率很小,从而产生的是激子发光的长波发射;当器件两个电极之间加的电压比较高时,有机薄膜层的场强很高, 在有机层形成的激子大部分被解离, 解离后的电子直接跃迁至LUMO(lowest unoccupancied molecular orbit),这些电子弛豫后从LUMO能级到HOMO(highest occupancied molecular orbit )能级直接辐射跃迁, 接着重新复合发光,从而产生短波发射。制作的固态阴极射线器件可以实现全色发光, 提高发光效率和加强蓝光发射。作者可以预期所研制出的这种SSCL器件必将引发平板显示领域一场新的革命性变革。     

亚微米纤芯光纤芯径大小与光学特性的关系

使用Maxell方程的严格解,研究了亚微米直径光纤的单模条件、传播常数、基模分布、传播效率、非线性系数等光学特性,发现亚微米纤芯直径光纤的单模条件与标准光纤相同,非线性系数在直径为700nm左右时最大;当光纤的直径小于1μm时,传播效率骤减.这些结果有助于新型微光通信和光纤传感器件的设计.     

Sagnac棱镜角公差与干涉光谱仪光谱分辨率的关系分析

根据干涉成像光谱仪光谱分辨率对角向差的要求,通过对实体Sagnac干涉仪结构和光路进行分析,从三个相互垂直的方向出发,研究了光谱分辨率和棱镜角公差之间存在的关系;并推导了满足光谱仪光谱分辨率要求的实体Sagnac干涉棱镜的角公差公式;用实例说明了关系式的应用方法,如果不考虑棱镜变形引起的色散及棱镜的面型误差和付氏镜的残余像差的影响,而只考虑棱镜的角误差对光谱分辨率的影响,则通常情况下干涉棱镜的角公差要求较严,约20″以内.     

负折射指数物质中金属线对电磁波的影响

构造两种结构负折射指数物质(NRM)，利用数值模拟计算两种结构的S参数.由于这种结构尺度比波长小，为精确利用有限积分技术(FIT)进行模拟.通过对这两种结构中金属线位置变化对金属谐振频率影响进行模拟，最后得出由于金属线与谐振环耦合，金属线对称破缺影响谐振环谐振频率和通带，并对等效负折射指数为负的频带产生影响. 关键词： 负折射率 左手物质 通带 金属线对称破缺     

Preparation and characterization of poly(lactic acid)/poly(methyl methacrylate) blend tablets for application in quantitative analysis by micro Raman spectroscopy

Poly(lactic acid) (PLA) is a biodegradable polymer that has a variety of applications, one of which is as biomaterial in surgery or as functional layers on implants, due to its compatibility with living tissue. This paper reports the possibilities of quantification of poly(lactic acid) (PLA) in a polymer matrix such as poly(methyl methacrylate) (PMMA) by micro Raman spectroscopy (MRS). Blends of amorphous poly(DL‐lactic acid) with poly(methyl methacrylate) were prepared by the procedure of dissolution/precipitation. Thermal properties of the blends such as the glass transition temperature (Tg) were characterized by differential scanning calorimetry (DSC). The PLA/PMMA blends exhibited only a single glass transition region, indicating that this system is miscible. The PLA/PMMA system obeys the Gordon–Taylor equation (Tg versus PLA content). Various concentration ratios of PLA blends were prepared to use as a basis for quantitative analysis by MRS. Intensities of the characteristic bands at 813 cm⁻¹ (νCOC of PMMA) and 873 cm⁻¹ (νC―COO of PLA) were used for the calculation. The calibration graph showed a good linear correlation with an R² value of 0.9985. On the basis of the calibration curve obtained, the determined content of several PLA/PMMA blends was in good agreement when compared with nominal contents. The limit of detection (LOD) and quantification (LOQ) were calculated by the calibration data set as signal‐to‐noise method. The relative standard deviation of this method was lower than 10% and the accuracy better than 4%. This study demonstrated that Raman spectroscopy provides an alternative non destructive method for quantitative analysis of PLA in a PMMA matrix. Copyright © 2015 John Wiley & Sons, Ltd.     

Accurate intensity calibration for low wavenumber (−150 to 150 cm−1) Raman spectroscopy using the pure rotational spectrum of N2

We report on an accurate intensity calibration method for low wavenumber Raman spectroscopy. It uses the rotational Raman spectrum of N₂. The intensity distributions in the rotational Raman spectra of diatomic molecules are theoretically well established. They can be used as primary intensity standards for intensity calibration. The intensity ratios of the Stokes and anti‐Stokes transitions originating from the same rotational levels are not affected by thermal population. Taking the effect of rotation–vibration interactions appropriately into account, we are able to calculate these intensity ratios theoretically. The comparison between the observed and calculated ratios of the N₂ pure rotational spectrum provides an accurate relative sensitivity curve (error ~5 × 10⁻⁴) in the wavenumber region of −150 to 150 cm⁻¹. We determine the temperature of water solely from the low wavenumber Raman spectra, using a thus calibrated spectrometer. The Raman temperature shows an excellent agreement with the thermocouple temperature, with only 0.5 K difference. The present calibration technique will be highly useful in many applications of low wavenumber quantitative Raman spectroscopy. Copyright © 2015 John Wiley & Sons, Ltd.     

Raman micro‐spectroscopy for quantitative thickness measurement of nanometer thin polymer films

The sensitivity of far‐field Raman micro‐spectroscopy was investigated to determine quantitatively the actual thickness of organic thin films. It is shown that the thickness of organic films can be quantitatively determined down to 3 nm with an error margin of 20% and down to 1.5 nm with an error margin of 100%. Raman imaging of thin‐film surfaces with a far‐field optical microscope establishes the distribution of a polymer with a lateral resolution of ~400 nm and the homogeneity of the film. Raman images are presented for spin‐coated thin films of polysulfone (PSU) with average thicknesses between 3 and 50 nm. In films with an average thickness of 43 nm, the variation in thickness was around 5% for PSU. In films with an average thickness of 3 nm for PSU, the detected thickness variation was 100%. Raman imaging was performed in minutes for a surface area of 900 µm². The results illustrate the ability of far‐field Raman microscopy as a sensitive method to quantitatively determine the thickness of thin films down to the nanometer range. Copyright © 2015 John Wiley & Sons, Ltd.     

Unveiling the correlation between non‐diffracting tractor beam and its singularity in Poynting vector

This paper investigates the singular optics of nonparaxial light beams in the near field when the light behaves as a tractor beam. New insights into the optical pulling force, which is usually represented by integrating the stress tensor at a black box enclosing the object, are interpreted by the optical singularity of the Poynting vector. The negative nonconservative pulling force originates from the transfer of the azimuthal Poynting vector to the longitudinal component partly owing to the presence of a scatterer. The separatrice pattern and singularity shifts of the Poynting vector unanimously exhibit a differentiable near‐field distribution in the presence of optical pulling force. A new method is established to calculate the near‐field optical force using the differential Poynting vector in the far field. The results obtained provide a clear physical interpretation of the light–matter interaction and manifest the significance of singular optics in manipulating objects.

     

Y分支器单元的有限差分光束传输法分析

Y分支器是集成光学中一种重要的器件单元。本文使用有限差分光束传输法(FD-BPM)系统地分析了Y分支器的工作机理,包括对称与非对称两种结构,其中着重对非对称Y分支器单元进行了分析,指出其欲完成模式分离所需满足的条件。通过对Y分支器的深入研究,我们也说明了FD-BPM法在对Y分支器及类似器件和单元的模拟分析中所具有的方便性和优越性,这为实际的设计制作工作提供了极好的基础。     

Study of natural diamonds by dynamic nuclear polarization-enhanced C nuclear magnetic resonance spectroscopy

The results of a study of two types of natural-diamond crystals by dynamic nuclear polarization (DNP)-enhanced high-resolution solid-state ¹³C nuclear magnetic resonance (NMR) are reported. The home-built DNP magic-angle spinning (MAS) ¹³C NMR spectrometer operates at 54 GHz for electrons and 20.2 MHz for carbons. The power of the microwave source was about 30 W and the highest DNP enhancement factor came near to 10³. It was shown that in the MAS spectra the ¹³C NMR linewidths of the I_b-type diamond were broader than those of I_aB3-type diamond. From the hyperfine structure of the DNP enhancement as a function of frequency, four kinds of nitrogen-centred and one kind of carbon-centred free radicals could be identified in the I_b-type diamond. The hyperfine structures of the DNP enhancement curve that originated from the anisotropic hyperfine interaction between electron and nuclei could be partially averaged out by MAS. The ¹³C polarization time of DNP was rather long, i.e. 1500 s, and the spin—lattice relaxation time (without microwave irradiation) was about 300 s, which was somewhat shorter than anticipated. Discussions on these experimental results have been made in this report.