PVP掺杂-ZrO2溶胶-凝胶工艺制备多层激光高反射膜的研究

以丙醇锆(ZrPr)为锆源,二乙醇胺(DEA)为络合剂,原位引入聚乙烯吡咯烷酮(PVP),在乙醇体系中成功地合成了PVP掺杂-ZrO2溶胶.采用旋涂法在K9玻璃基片上制备了PVP-ZrO2单层杂化薄膜.用不同掺杂量的PVP-ZrO2高折射率膜层与相同的SiO2低折射率膜层交替沉积四分之一波堆高反射膜.借助小角X射线散射研究胶体微结构,用红外光谱、原子力显微镜、紫外/可见/近红外透射光谱、椭圆偏振仪以及1064nm的强激光辐照实验对薄膜的结构、光学和抗激光损伤性能进行表征.研究发现,体系组成的适当配置可以在溶胶稳定的前提下实现ZrPr的充分水解,赋予薄膜良好的结构、光学和抗激光损伤性能.杂化体系中,DEA与ZrPr之间强的配合作用大大降低了ZrO2颗粒表面羟基的活性,使得PVP大分子只是以微弱的氢键与颗粒的表面羟基作用而均匀分散于ZrO2颗粒的周围,对颗粒的形成和生长无显著影响.因而在实验研究范围内,随PVP含量的增大,PVP-ZrO2杂化膜层的折射率和激光损伤阈值均无显著变化.但是,薄膜中均匀分布的PVP柔性链可以有效促进膜层应力松弛,显著削弱不同膜层之间的应力不匹配程度、大大方便多层光学薄膜的制备.当高折射率膜层中PVP的质量分数达到15%-20%时,膜层之间良好的应力匹配使得多层高反射膜的沉积周期数可达到10以上.沉积1O个周期的多层反射膜,在中心波长1064nm处透射率约为1.6%-2.1%,接近全反射特征,其激光损伤阈值为16.4-18.2J/cm2(脉冲宽度为1ns).     

近红外光谱技术在食品产地溯源中的研究进展

食品产地溯源是建立食品质量安全追溯制度的重要组成部分,也是保障食品质量安全的有效手段.近红外光谱(near infrared spectroscopy,NIRS)技术因其快速、无污染、操作简单等优点受到人们的青睐,是用于食品产地溯源的有效技术.对比了几种用于食品产地溯源的技术的优缺点,阐述了近红外光谱技术分析的基本原理...     

N掺杂锐钛矿TiO2光学性能的第一性原理研究

用平面波赝势方法(PWP)计算了N掺杂锐钛矿型TiO2前后的光学特性,即介电函数虚部ε2(w),光学吸收系数I(w)和反射率R(w).并从能带结构上解释了为什么掺N后锐钛矿型TiO2的光学谱在2.93,3.56和3.97 eV处相对掺杂前会出现3个峰值的原因.从光谱图上分析得出,掺杂后TiO2要发生红移现象,实验现象证实了这一结果.     

Influence of reaction gas flows on the properties of SiGe:H thin film prepared by plasma assisted reactive thermal chemical vapour deposition

A new preparing technology, very high frequency plasma assisted reactive thermal chemical vapour deposition （VHFPA-RTCVD）, is introduced to prepare SiGe：H thin films on substrate kept at a lower temperature. In the previous work, reactive thermal chemical vapour deposition （I~TCVD） technology was successfully used to prepare SiGe：H thin films, but the temperature of the substrate needed to exceed 400℃. In this work, very high frequency plasma method is used to assist RTCVD technology in reducing the temperature of substrate by largely enhancing the temperature of reacting gases on the surface of the substrate. The growth rate, structural properties, surface morphology, photo- conductivity and dark-conductivity of SiGe：H thin films prepared by this new technology are investigated for films with different germanium concentrations, and the experimental results are discussed.     

Long-lived emission from platinum(II) terpyridyl acetylide complexes

Photoluminescence with high quantum yield and long lifetime from a triplet metal-to-ligand charge transfer (MLCT) excited state in fluid solution at room temperature has been observed for a series of platinum(II) 4'-p-tolyl-terpyridyl acetylide complexes.     

Controlled photocyclization, photodimerization, and photoisomerization of stilbazole salts within Nafion membranes

[reaction: see text] Water- and methanol-swollen Nafion membranes were used as microreactors to successfully control the photochemical reaction pathway of stilbazole derivatives. Of particular interest is the production of azaphenanthrene (the product not obtainable in homogeneous solution) in high yield under high bulk concentration.     

Photoisomerization of norbornadiene group in a rigid bichromophoric compound initiated by remote keto chromophore: long-distance through-bond triplet energy transfer

A diad compound 3β(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-an-drost-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at λ > 300 nm selectively excited the keto chromophore. After intersystem crossing, the triplet energy of the keto group was transferred to the NBD group with 18.6% efficiency via a through-bond mechanism, resulting in the isomerization of the latter group to the quadricyclane group.     

A luminescent chemosensor with specific response for Mg2+

A novel chemosensor, a cyclometalated platinum(II) bipyridyl acetylide complex containing a monoazacrown moiety in the acetylide ligand, which can signal Mg(2+) specifically and display large changes both in color and in luminescence intensity upon complexation with Mg(2+), is described.     

Crystal structure of 2,3-bis(2-pyridyl)-5, 8-dimethoxyquinoxaline

Crystals of 2,3-bis(2-pyridyl)-5,8-dimethoxyquinoxaline (bpdmq) were examined using X-ray diffraction analysis: Monoclinic, space group P2 ₁/n with a = 6.9362(14) Å, b =17.285(4) Å, c =13.583(3) Å, =96.21(3)°, V =1619.0(6) ų, Z = 4. The crystal structure indicates that the title compound consists of quinoxaline ring system substituted with two pyridine rings and two methoxy groups. Two pyridine rings form dihedral angles of 39.8 and 44.1° with the mean planar quinoxaline ring, and a dihedral angle of 67.1° with each other. The orientation of the pyridine rings is such that their N atoms face each other. There exist significant – interactions responsible for the formation of the stacks along the a-axis of the crystal packing.     

Photocatalytic hydrogen production from hantzsch 1,4-dihydropyridines by platinum(II) terpyridyl complexes in homogeneous solution

1,4-Dihydropyridines have been photocatalytically oxidized to pyridines by platinum(II) terpyridyl complexes with the generation of hydrogen in homogeneous solution. The hydrogen production proceeds in quantitative yield and with great catalytic turnover.