Cr：Mg2SiO4晶体红外光致发光谱的研究

报道了在室温和液氮温度下分别用1064nm和532nm激光诱导的Cr:Mg_2SiO_4晶体的红外光致发光谱,并详细分析光谱的结构和特点.在假设Cr:Mg_2SiO_4晶体中同时存在(CrO_6)~(9-)和(CrO_4)~(4-)两种络离子的基础上讨论了红外光致发光的产生机理,理论计算证明假设是合理的.     

用于红外探测的新型冷却器—脉冲管制冷机

脉冲管制冷技术近年来的突破性进展,使其可在相当多的领域得到应用。本文通过分析和比较,结合作者等人近几年来的研究结果,给出脉冲管制冷机应用于红外探测器件冷却的可行性。     

Wick-Ordered Entire Functions of the Indefinite Metric Free Field

We present a simple and general method for constructing Wick-ordered entire functions of free fields with an indefinite metric, based on using an appropriate generalization of the Paley–Wiener–Schwartz theorem.     

Effects of several lanthanide trichloride hydrates on the melting behavior and spherulitic superstructure of poly(ethylene oxide)

Binary mixtures of poly(ethylene oxide) (PEO) with the trichloride hydrates of lanthanum, cerium, europium, terbium, and ytterbium have been studied with calorimetry, polarized optical microscopy, and infrared spectroscopy. Melting‐point depression of the PEO‐rich phase occurs in all cases. At sufficiently high concentrations of the low molecular weight lanthanide complex, crystallization of the polymer is absent. The lighter lanthanides with larger ionic radii, such as lanthanum and cerium, are more effective in suppressing PEO crystallization from solution or the molten state because they are more oxophilic. The spherulitic superstructure of PEO disappears at rather low concentrations of the lanthanide salts, between 2 and 8 mol % Ln³⁺. Lanthanum and terbium are most efficient at disrupting the formation of PEO spherulites, and europium is least efficient. Infrared spectroscopy identifies twisting and wagging vibrational absorptions of CH₂ groups in the polymer that are sensitive to the morphologies of these mixtures. Modifications of the PEO infrared absorbances in the presence of these five lanthanide salts correlate more closely with the presence or absence of major PEO melting, not the formation of a spherulitic superstructure. The phase behavior is rather simple, with no evidence of eutectic solidification upon cooling from the molten state. Multiple melting endotherms are observed in the differential scanning calorimetry heating traces of binary mixtures containing 8 mol % Yb³⁺ and between 10 and 20 mol % Eu³⁺, but the concentration dependence of these first‐order endothermic transitions is not characteristic of eutectic phase behavior. The presence of trivalent cations, such as Eu³⁺ or Yb³⁺, in these complexes perturbs the crystallization kinetics of PEO upon cooling from the molten state, as well as the melting behavior upon heating. Ion–dipole or electrostatic interactions between the lanthanide cation and the ether oxygen of PEO might alter the surface free energy at the periphery of the crystalline lamellae and perturb the chain‐folding characteristics of PEO. Consequently, coupling between the amorphous matrix and the PEO crystallites is strengthened, and this provides stability for the existence of multiple‐chain‐folded crystals composed of rather thin lamellae that could be responsible for multiple melting behavior. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2200–2213, 2003     

Polyethylene terephthalate–multiwall nanotubes nanocomposites: Effect of nanotubes on the conformations,crystallinity and crystallization behavior of PET

PET‐nanotube composite samples were manufactured by mixing neat PET with a PET‐multiwall carbon nanotube masterbatch. Fourier transform infrared (FTIR) spectroscopy was utilized to monitor the gauche and trans conformations of the polymeric chains with respect to the nanotube content. The crystallinity as well as the crystallization behavior of the polymer were studied via differential scanning calorimetry (DSC). An increase of the trans conformations and crystallinity was recorded at low NT contents followed by a sharp decrease at 1 wt % of nanotubes, further addition of nanotubes led once again to increase of the trans conformations and crystallinity. This behavior was attributed to the aggregations formation which as shown via transmission electron microscopy (TEM) was initiated at concentrations above 0.5 wt %. Discordance between the FTIR and DSC results in the case of the PET sample showed that the later bears relatively more trans non‐crystalline conformers than the nanocomposite samples. Thus it appears that the nanotubes incorporate the trans non‐crystalline segments into the crystalline phase. This work has shown that even a minor addition of carbon nanotubes (even 0.1 wt %) alters the crystallization behavior of the polymer dramatically, yielding a novel nanocomposite material rather than a simple mixture of two ingredients. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 668–676, 2008     

Photochemistry and initiation behavior of phenylethynyl onium salts as cationic photoinitiators

Phenyl(phenylethynyl)iodonium hexafluorophosphate and diphenyl(phenylethynyl)sulfonium hexafluorophosphate were synthesized for application as cationic photoinitiators using simple, straightforward methods. Quantification of the purity of the counterion was determined by FTIR analysis with subsequent mathematical peak deconvolution. Photodecomposition products for direct irradiation were determined in steady state photolysis experiments yielding diphenyl sulfide and phenyl(phenylethynyl) sulfide or iodobenzene, respectively, as main products. Heterolytic cleavage was proposed as main photodecomposition pathway because low yields of phenylacetylene radical recombination products and no photoproducts generated by phenyl radicals, including benzene, were detected. High activity as photoinitiators was verified by photo‐DSC experiments in direct irradiation and in photosensitized initiation using 9,10‐dibutylanthracene, 2‐isopropylthioxanthone, and surprisingly also benzophenone as sensitizers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3419–3430, 2009     

无源红外方位标研究

提出在现有条件下利用激光实现无源红外方位标的思路，并通过详细计算与分析，论述了无源红外方位标的可行性。     

连续CO2激光对红外窗口材料损伤研究

研究了连续ＣＯ２激光对几种红外窗口材料的表面损伤特性，研究表明，损伤机制在于杂质缺陷吸收造成的热冲击应力破坏。深入研究了杂质缺陷密度、焦斑与材料损伤阈值的关系，并建立了一个损伤模型。同时分析了热冲击应力破坏方式。     

一种高品质中空金属光波导

讨论了高品质中空金属光波导的工作原理及其制作工艺，制备了以金和银作为波导材料的中空波导管，并对空芯以及充入不同透明液体的液芯波导的透光特性进行了测试，结果表明：与中空介质波导相比，中空金属波导具有光传输损耗低，透过率对波导弯曲与失调不甚敏感等优点；而液芯金属波导的透光效率与透明材料的折射系数无关。文中描述了在特定波段内“中空光纤”的原理，并报道了Ｈｅ－Ｎｅ和ＣＯ２激光在中空金壁波导传输的实验结果。     

Far-infrared detector based on HgTe/HgCdTe superlattices

HgTe/Hg_0.05Cd_0.95Te superlattices (SLs) were grown on (112)B oriented Cd_0.96Zn_0.04 Te substrates using molecular beam epitaxy (MBE). The SLs, consisting of 100 periods of 80-Å-thick HgTe wells alternating with 77-Å-thick Hg_0.05Cd_0.95Te barriers, were designed to operate as detectors in the far-infrared (FIR) region. Infrared absorption spectroscopy, high-resolution transmission electron microscopy (TEM), Hall effect measurements, and x-ray diffraction were used to characterize the superlattice layers. A series of annealing experiments were initiated to quantify the temperature-dependent interdiffusion of the HgTe wells and Hg_0.05Cd_0.95Te barriers and consequently their degradation, which shifts the absorption edges of the SLs to higher energies, since a high-temperature ex situ anneal is normally required in order to produce the p-type material required for a photovoltaic detector. Results from infrared absorption spectroscopy, TEM, and Hall effect measurements for the annealed samples are presented. A FIR SLs single-element photoconductive (PC) device was designed and fabricated. Both material characterization and device testing have established the applicability of the HgTe/Hg_0.05Cd_0.95Te SLs for the FIR region.