Thermal‐Induced Formation of a Three‐Dimensional Nanoplasmonic Sensor from Ag Nanocubes with High Stability and Reusability

Nanoplasmonic sensors based on the localized surface plasmon resonance (LSPR) of noble metal nanoparticles have many advantages, such as real‐time detection, no need for reagent labelling, and no use of complicated equipment. However, the nanoplasmonic sensors with two dimensional structures usually suffer from a low LSPR signal and thus low sensitivity due to the low density of the nanoparticles. In addition, complicated surface functionalization is always required to suppress the non‐specific binding of the analyst to the substrate of the sensor, because the two types of surface, that is, metal and substrate surfaces, are simultaneously exposed to the reaction medium. To overcome these problems, an innovative thermal‐induced method has been proposed in the present work, to construct three dimensional (3D) nanostructure of Ag nanocubes on both surfaces of the substrate by using the unique amphiphilic property of 2‐diethylaminoethanethiol. The prepared nanoplasmonic sensor is highly sensitive due to the high density of 3D structure of the nanoparticles and the low non‐specific binding since only one type of surface is exposed. To enhance the stability of the sensor, a thin SiO₂ overlayer was formed on the surface without using an additional coupling agent. Furthermore, the Ni^II‐nitriloacetic acid (Ni^II‐NTA) complex was covalently bound on the surface, so that the regeneration and reuse of the sensor becomes easy. Therefore, the easy fabrication, high stability, and good reusability of this 3D LSPR sensor makes our method competitive for the development of nanoplasmonic sensors.     

氧碘化学激光器增益谱线的实验研究

 利用可调谐二极管激光器为探测光源, 直接测量了氧碘化学激光器的增益谱线的精细结构及其各谱线所占比例。同时用碘原子吸收池标定了六条谱线。     

氧碘化学激光器UR-90腔光束质量研究

 概括了光束质量的表示方法, 由衍射极限倍数的定义出发, 提出重点在于选取光斑直径, 而且可把光斑测量归结到电子测试仪对剪切电平的测量上。给出了电子测试仪的测试原理, 由所测光斑直径计算了氧碘化学激光器U R290腔的光束质量指标—衍射极限倍数, 达到了1.2～1.6倍衍射极限, 最后进行了误差讨论。     

Poly(DR-1/MMA)聚合物波导中Cerenkov倍频辐射的实验研究

本文报道采用电晕极化技术和旋转涂布方法制备Poly(DR-1/MMA)型有机共聚物薄膜波导生成二次谐波(SH)的实验研究.Q开关Nd:YAG激光器的1.064μm波长的输入光在极化聚合物波导中经Cerenkov型相位匹配产生0.532μm的倍频辐射光,总的转换效率达1.25×10^-3%.     

共轭读出法消除光致变色材料全息记录中的相位畸变

采用有机光致变色材料-吲哚俘精酰胺/PMMA薄膜作为可擦写全息记录介质,建立了一种能消除全息光存储中相位畸变的光路.此光路采用参考光的相位共轭光再现全息图,能有效消除物光路中由于光学元件失调和记录材料缺陷引起的相位畸变,是全息光存储中提高再现像像质的一种有用光路.     

气相色谱在食品检测方面的应用及进展

对近年来气相色谱技术在食品检测方面的应用进行综述,主要包括农药残留分析,食品添加剂分析,兽药残留分析以及食品包装材料中挥发物分析,并对未来的应用进行了展望。     

Phenyl-calix[4]arene-based fluorescent sensors: cooperative binding for carboxylates

Tetrakis-(4-carbamoylphenyl)-substituted and tetrakis-(4-amidophenyl)-substituted calix[4]arenes as well as the monomeric biphenylcarbamate have been synthesized as fluorescent receptors for anion sensing. Their binding properties with various anions including F-, CH3COO-, Ph-COO-, and H2PO4- were investigated by fluorescence titrations, Job plot experiments, 1H NMR spectroscopies, and ESI-MS measurements. Importantly, we have found that calix[4]arene-based sensors exhibit greatly enhanced binding affinity and selectivity toward carboxylates. The binding associations of tetrakis-(4-carbamoylphenyl)-substituted calix[4]arene for carboxylates are 1-2 orders of magnitude greater than those of the monomeric biphenylcarbamate sensor. Such an enhancement in the binding affinity and selectivity is attributed to the cooperative binding of the multiple ligating groups as revealed from the ab inito DFT calculations. Although tetrakis-(4-amidophenyl)-substituted calix[4]arene exhibited relatively weaker binding affinity toward anions, its superior binding selectivity for acetate ion over fluoride ion is evident. Our results also suggest that carbamate functionality is a useful H-bond donor for hydrogen-bonding interactions in molecular recognition and supramolecular chemistry.     

Excited‐State Deactivation of Branched Phthalocyanine Compounds

The excited‐state relaxation dynamics and chromophore interactions in two phthalocyanine compounds (bis‐ and trisphthalocyanines) are studied by using steady‐state and femtosecond transient absorption spectral measurements, where the excited‐state energy‐transfer mechanism is explored. By exciting phthalocyanine compounds to their second electronically excited states and probing the subsequent relaxation dynamics, a multitude of deactivation pathways are identified. The transient absorption spectra show the relaxation pathway from the exciton state to excimer state and then back to the ground state in bisphthalocyanine (bis‐Pc). In trisphthalocyanine (tris‐Pc), the monomeric and dimeric subunits are excited and the excitation energy transfers from the monomeric vibrationally hot S1 state to the exciton state of a pre‐associated dimer, with subsequent relaxation to the ground state through the excimer state. The theoretical calculations and steady‐state spectra also show a face‐to‐face conformation in bis‐Pc, whereas in tris‐Pc, two of the three phthalocyanine branches form a pre‐associated face‐to‐face dimeric conformation with the third one acting as a monomeric unit; this is consistent with the results of the transient absorption experiments from the perspective of molecular structure. The detailed structure–property relationships in phthalocyanine compounds is useful for exploring the function of molecular aggregates in energy migration of natural photosynthesis systems.     

Chiral conversion and memory of TPPS J-aggregates in complex micelles: PEG-b-PDMAEMA/TPPS

In the presence of tryptophan (Trp), complex micelles were prepared by 5,10,15,20-tetrakis(4-sulfonatophenyl) porphyrin (TPPS) and poly(ethylene glycol)-block-poly(2-(dimethylamino)ethyl methylacrylate) (PEG-b-PDMAEMA) in aqueous solutions at pH 1.8. Different mixing sequences led to different morphologies. Spheres and nanorods of small size were obtained in sequence I (P/Trp+TPPS) where TPPS was added into the mixed solution of PEG-b-PDMAEMA and Trp. More nanorods of larger length were achieved in sequence II (TPPS/Trp+P) where the copolymer was added as the last component. Two types of supramolecular chirality of TPPS aggregates caused by mixing sequences were investigated. In (P/Trp+TPPS), the circular dichroism (CD) signal of H-band was in line with the chirality of Trp while that of J-band exhibited an opposite signal (Chirality I). In (TPPS/Trp+P), chiral signals at both H- and J-bands followed that of Trp (Chirality II). The conversion between the two types of chirality can be accomplished by modulating the molar ratio of the repeating units on block PDMAEMA to TPPS, or a cycle of pH 1.8-5.5-1.8 processing on the micelle solution. In addition, the supramolecular chirality can be memorized via strong electrostatic interaction with achiral copolymer even after removal of the chiral template, but only Chirality II can be cyclically "switched-off-on".