Fluorene‐Carbazole Dendrimers: Synthesis,Thermal, Photophysical and Electroluminescent Device Properties

Novel hole‐transporting dendrimeric molecules containing dioctylfluorene, spirobi(fluorene) and spiro(cylododecane‐fluorene) as the core unit and different numbers of carbazole and thiophene moieties as the peripheral groups are synthesized. All the dendrimers are characterized by ¹H NMR, ¹³C NMR, FTIR, UV–vis, PL spectroscopy, and MALDI‐TOF. They are thermally stable with high glass transition and decomposition temperatures and exhibit chemically reversible redox processes. They are used as the hole‐transporting layer (HTL) material for multilayer organic light emitting diodes (OLEDs) with a low turn‐on voltage of around 2.5 V and a bright green emission with a maximum luminance of around 25400 cd m^?2.     

上海光源插入件光束线白光狭缝设计

上海光源是第三代同步辐射装置,第一期工程拟建造7条光束线中有5条选用插入件光源,其中,三条由波荡器(Undulator)引出,两条由扭摆器(Wiggler)引出。插入件光源产生高功率同步辐射,会给插入件光束线部件设计带来极大的挑战。为此,我们为插入件光束线设计了新型L形白光狭缝,本文主要介绍了该白光狭缝设计。     

Dimedone and phenylazo dimedone chelates of europium as emitters in polymers

Transparent polymers when incorporated with strongly fluorescent europium chelates were found to be responding to excitation with UV radiation. In this work, two novel europium chelates have been synthesized using the β‐diketones dimedone and phenylazo dimedone along with 1,10‐phenanthroline. These chelates were characterized by elemental analyses, magnetic susceptibility measurements, UV, IR, and ESI mass spectral techniques. The chelates synthesized with metal : β‐diketone : 1,10‐phenanthroline ratio 1 : 3 : 1 were incorporated into polymer matrices. Four polymers, polyethylene vinyl acetate or acetate (EVA), polystyrene (PS), poly methyl methacryalate (PMMA), and polyethylene glycol (PEG) were used for the studies. All these, except the liquid oligomer PEG were cast into thin films. PEG was used as such for the studies. The photoluminescence spectra of the plain polymers were found to be having peaks very close to the absorption peaks of the polymers doped with europium chelate. This observation can be used in optical devices. Thermal analyses like TG/DTG/DTA of the polymer films were conducted to ascertain the thermal stability of the material. The SEM analyses of the films indicated a smooth surface with uniform distribution of the doped chelate. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Halide Perovskite Nanocrystals for Next‐Generation Optoelectronics

Colloidal perovskite nanocrystals (PNCs) combine the outstanding optoelectronic properties of bulk perovskites with strong quantum confinement effects at the nanoscale. Their facile and low‐cost synthesis, together with superior photoluminescence quantum yields and exceptional optical versatility, make PNCs promising candidates for next‐generation optoelectronics. However, this field is still in its early infancy and not yet ready for commercialization due to several open challenges to be addressed, such as toxicity and stability. Here, the key synthesis strategies and the tunable optical properties of PNCs are discussed. The photophysical underpinnings of PNCs, in correlation with recent developments of PNC‐based optoelectronic devices, are especially highlighted. The final goal is to outline a theoretical scaffold for the design of high‐performance devices that can at the same time address the commercialization challenges of PNC‐based technology.     

谱学显微光束线光斑水平漂移分析与检测

为提高上海光源搭建的国内首条软X射线谱学显微光束线站的整体性能,分析了其分光装置一变包含角平面光栅单色仪在波长扫描过程中影响谱学显微光束线光斑水平漂移的各个因素,推导出了各因素与光斑水平漂移的传递关系,并结合具体要求进行了误差分配.针对光斑水平角漂移重复精度的检测,采用自准直原理,构建了测试系统.利用该系统,完成了谱学显微光束线站光斑水平漂移重复精度的离线检测,其结果为0.67″,满足设计指标1″的要求.对安装调试后的束线进行了总体性能测试,结果均满足谱学显微设计和使用要求.由此表明,提出的对谱学显微光束线光斑水平漂移误差来源的分析及检测方法,有效保证了束线性能的实现.     

UV-Induced Charge-Transfer States in Short Guanosine-Containing DNA Oligonucleotides

Charge transfer has proven to be an important mechanism in DNA photochemistry. In particular, guanine (dG) plays a major role as an electron donor, but the photophysical dynamics of dG-containing charge-transfer states have not been extensively investigated so far. Here, we use UV pump (266 nm) and picosecond IR probe (∼5–7 μm) spectroscopy to study ultrafast dynamics in dG-containing short oligonucleotides as a function of sequence and length. For the pure purine oligomers, we observed lifetimes for the charge-transfer states of the order of several hundreds of picoseconds, regardless of the oligonucleotide length. In contrast, pyrimidine-containing dinucleotides d(GT) and d(GC) show much faster relaxation dynamics in the 10 to 30 ps range. In all studied nucleotides, the charge-transfer states are formed with an efficiency of the order of ∼50 %. These photophysical characteristics will lead to an improved understanding of DNA damage and repair processes.     

上海光源红外束线中CVD金刚石窗的参数对红外透射率的影响

同步辐射红外光束线站的红外光束经过束线中金刚石窗时,发生多重反射,导致不同波数的透射率发生变化,在傅里叶变换红外光谱仪中造成额外噪声。结合上海光源BL01B红外光源特性,研究金刚石窗不同参数(如楔角、安装角度、直径和厚度等)对红外透射率的影响。计算结果表明,金刚石窗各参数对同步辐射红外束线透射率有很大影响。     

北京同步辐射1W2B生物大分子光束线兼用模式

模拟并优化了北京同步辐射1W2B生物大分子光束线兼用模式下的光束性能。通过实际测量光束的性能参数,并与专用模式进行对比,验证了1W2B光束线兼用模式的可行性,即在兼用模式条件下,1W2B光束线依然满足生物大分子晶体多波长反常散射等实验要求,大幅增加了北京同步辐射生物大分子晶体学实验的机时,提高了该光束线的利用效率。     

MATLAB神经网络分析上海光源光束线的运行数据

上海光源光束线运行状态的记录数据具有非线性、复杂和无规律的特点,利用神经网络可有效地分析和处理这些数据。选用Matlab进行数据提取和分析,介绍了Matlab与archive数据库间的数据连接,并用神经网络模式识别对光束线设备运行的状态参量进行数据训练,给出了BL13W光束线站单色器中某一温度运行参量的分类预警及其运行数据分析处理的结果。     

用于同步辐射光束线工程的三维精密调整平台

介绍了用于同步辐射光束线工程的三维精密调整平台结构原理,其特点是:结构紧凑,承载量大,精度高;采用步进电机驱动实现三维精密运动,并通过数字电路与软件实现其智能化,同时备有手动工作模式.