Photochemistry and photophysics of poly(organophosphazenes) and related compounds: A review. II. Bimolecular reactions

In the second part of this review we highlight the bimolecular reactions (hydrogen abstraction, and energy or electron transfer) that take place in the photochemistry of poly(organophosphazenes). Both inter-molecular interactions (i.e. between excited free chromophores and ground state groups attached to the phosphazenes, or between excited phosphazene substituents and external quenchers) and intra-molecular processes (i.e. between excited and ground state groups geminally attached to the same phosphorus or supported to different phosphorus along the polyphosphazene skeleton) are exploited. Suggestions are given on the possible practical application of these reactions in different photochemical domains, e.g. heterogeneous-phase photosensitization, photocrosslinking, photoconductivity, microelectronics, light-induced radical polymerization of vinyl monomers, etc.     

超高真空精密四刀狭缝的结构原理及有限元分析

针对上海光源X射线干涉光刻(XIL)光束线对狭缝精度的要求,提出了一种应用于超高真空的精密四刀狭缝机构及热缓释方案.给出了四刀狭缝机构的工作原理,其四个缝片独立运动,采用线性驱动装置及精密直线导轨来实现开合.根据XIL光束线的特点,设计了一种合理有效的热缓释方案,对缝片进行了热-结构耦合分析.对狭缝的精度指标进行了测试.结果显示:该四刀狭缝的分辨率优于0.1μm、运动重复精度优于2μm、刀口直线度优于2.5 μm、平行度优于0.5 mrad,可以精确实现狭缝在水平和垂直方向-5～250 μm的开度,缝片在热负载下的最大热变形控制在0.034μm.得到的结果表明,该精密四刀狭缝具有高的精度和稳定性,可满足XIL光束线的使用要求,现已实际使用并制备出了100 nm周期的刻蚀线结构.     

Micropatterning of polydiacetylene based on a photoinduced chromatic transition and mechanism study

A photoinduced chromatic transition from blue to red for the polydiacetylene 10,12‐pentacosadiynoic acid has been studied. This transition produces an obvious change in the ultraviolet–visible absorption and fluorescence emission spectra. A two‐dimensional micropattern has been realized on the basis of this change and imaged with a confocal fluorescence microscope. Detailed information on the mechanism of the chromatic transition has been obtained by the application of resonance Raman and Fourier transform infrared methods. The results indicate that the conformational change of alkyl side chains constricted by hydrogen‐bonded head groups imposes strain on the polymer backbone and finally leads to a drastic decrease in the π‐electron‐conjugation length. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 942–946, 2007     

计量线高次谐波的定量研究

采用自制的840/mm金膜自支撑透射光栅和美国IRD公司的AXUV100G光电二极管探测器,定量研究了光谱辐射标准和计量光束线在5~140 nm波段的高次谐波。研究了Al、Si₃N₄和Zr滤片在不同能量范围对高次谐波的抑制作用,给出了实验数据和曲线。实验结果显示:在5~15 nm波段,不用任何滤片高次谐波的信号强度＜7％;在5~34 nm波段,适当的选用Al、Si₃N₄和Zr滤片可有效地抑制高次谐波,将高次谐波占基波的积分信号强度比例控制在＜14％,经探测器的量子效率修正后高次谐波的百分比在6.5％以内。在经过MgF₂窗滤波的115~140 nm波段,高次谐波的衍射峰几乎完全被抑制。这一研究为软X射线和极紫外的光谱计量、探测器定标和光学元件性能测试奠定了基础。     

Material Crystallinity as a Determinant of Triplet Dynamics and Oxygen Quenching in Donor Polymers for Organic Photovoltaic Devices

This paper is concerned with the photophysics of triplet excitons in conjugated donor polymers, and their quenching by molecular oxygen. These photophysics are assayed by transient absorption spectroscopy, and correlated with X‐ray diffraction measurements of relative material crystallinity. Eleven different donor polymers are considered, including representatives from several classes of donor polymers recently developed for organic solar cell applications. Triplet lifetimes in an inert (nitrogen) environment range from <100 ns to 5 μs. A remarkably quantitative correlation is observed between these triplet lifetimes and polymer XRD strength, with more crystalline polymers exhibiting shorter triplet lifetimes. Given the broad range of polymers considered, this correlation indicates that material crystallinity is the dominant factor determining triplet lifetime for the polymers studied herein. The rate constant for oxygen quenching of these triplet states, determined from a comparison of transient absorption data under inert and oxygen environments, also show a correlation with material crystallinity. Overall these dependencies result in the yield of oxygen quenching of polymer triplet states increasing strongly as the crystallinity of the polymer is reduced. These photophysical data are compared with photochemical stability of these donor polymers, assayed by photobleaching studies of polymer films under continuous light exposure in an oxygen environment. A partial correlation is observed, with the most stable polymers being the most crystalline, exhibiting negligible oxygen quenching yields. These results are discussed in terms of the likely origins of the correlations between material crystallinity and photophysics, and in terms of their implications for the environmental stability of such donor polymers in optoelectronic devices.     

Evidence for ciliary pigment localization in colored ciliates and implications for their photosensory transduction chain: a confocal microscopy study

In this study we report for the first time the localization of a photoreceptor pigment in the cilia of the colored heterotrich ciliates Blepharisma japonicum red and blue form, Fabrea salina, and Stentor coeruleus, as result of a confocal microscopy investigation. Optical sectioning confocal microscopy has been used for studying the spatial distribution of the pigment in the cell body, surprisingly showing that, besides its expected presence in the cortical region immediately below the cell membrane, it is located in the cilia too. In order to ascertain possible differences in the pigment fluorescence properties along the cell body, we have measured emission spectra from different parts of it (anterior, posterior, and cilia). Our results clearly indicate that in all cases the spectra are the same, within experimental errors. Finally, we have evaluated the pigment relative fluorescence efficiency of these ciliates. In an ordered scale from lower to greater efficiency, we have S. coeruleus, B. japonicum blue, B. japonicum red, and F. salina. The possible implications of our findings for the process of photosensory transduction are discussed.     

卟啉类第二代光敏剂的发展

本文对目前用于光动力治疗的以卟啉为基础的第二代光敏剂进行了综述，这些光敏剂中的大部分已进入临床或临床前试验，光物理性质研究表明它们是很有前途的光动力药物。本文同样介绍了连接生物分子和硼烷的卟啉衍生物，作为光序剂，它们具有非常光明的前途。     

Thermal curing of glass‐epoxy prepregs by luminescence spectroscopy

In this study, we investigated the application of the luminescence spectroscopy technique in steady‐state conditions to study glass fiber‐epoxy F161 prepregs. We conducted this study by comparing the results obtained from the intrinsic fluorescence with Fourier transform near infrared spectroscopy. The extrinsic fluorescence of 9‐anthroic acid (9‐AA) was also used. Fourier transform infrared spectroscopy was also used to characterize the epoxide resin. The prepregs containing 9‐AA and those that did not were heat‐treated at 177°C (F161) for 1100 min at a 2°C/min heating rate. The results obtained by both methods indicated that the crosslinking reaction could be monitored by analysis of the spectral changes of the emission bands of the prepreg and 9‐AA. The intrinsic emission at 320 nm was attributed to the fluorophore group containing the epoxy ring and was used to calculate the conversion degree. The photophysical behavior of the 9‐AA probe indicated a reduction of free volume of the polymeric matrix with curing process. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

New Halogenated Water‐Soluble Chlorin and Bacteriochlorin as Photostable PDT Sensitizers: Synthesis,Spectroscopy, Photophysics,and in vitro Photosensitizing Efficacy

Chlorin and bacteriochlorin derivatives of 5,10,15,20‐tetrakis(2‐chloro‐5‐sulfophenyl)porphyrin have intense absorptions in the phototherapeutic window, high water solubility, high photostability, low fluorescence quantum yield, long triplet lifetimes, and high singlet oxygen quantum yields. Biological studies revealed their negligible dark cytotoxicity, yet significant photodynamic effect against A549 (human lung adenocarcinoma), MCF7 (human breast carcinoma) and SK‐MEL‐188 (human melanoma) cell lines upon red light irradiation (cutoff λ<600 nm) at low light doses. Time‐dependent cellular accumulation of the chlorinated sulfonated chlorin reached a plateau at 2 h, as previously observed for the related porphyrin. However, the optimal incubation time for the bacteriochlorin derivative was significantly longer (12 h). The spectroscopic, photophysical, and biological properties of the compounds are discussed in relevance to their PDT activity, leading to the conclusion that the bacteriochlorin derivative is a promising candidate for future in vivo experiments.