激发态质子转移分子2-(2'-羟基苯基)苯并噻唑溶液的全光开关效应

研究了激发态质子转移(ESPT)分子2-(2'-羟基苯基)苯并噻唑(HBT)在不同极性溶剂中的光开关行为,探讨了溶剂极性对HBT分子光开光效应的影响.揭示了光开关脉冲信号的形成原因,建立了基于光诱导HBT分子激发态非线性折射效应的皮秒全光开关的理论模型.根据对时间响应函数的理论计算和实验结果分析,确定了光开关脉冲信号下降前沿和上升后沿的形成机理以及影响因素,并提出了增强光开关信号下降前沿的关断深度,提升上升后沿的恢复速度的有效途径和方法.本文工作为制成皮秒量级关断,微秒甚至纳秒量级重新打开的快速全光开关器 关键词： 全光开关 2-(2'-羟基苯基)苯并噻唑(HBT) 激发态质子转移 非线性光学特性     

基于酞菁铜的有机光敏场效应管

制备了基于酞菁铜(CuPc)的有机光敏场效应晶体管,对器件的光敏特性进行了研究。实验结果表明,基于金源漏电极的器件,在波长655 nm,光强100 mW/cm²的光照下,明/暗电流比约为0.4,光响应度约为2.55 mA/W;而铝为源漏电极的器件,可以获得高达10⁴的明/暗电流比,但光响应度降低为0.39 mA/W。     

基于近红外聚集诱导发光分子的磁性纳米材料用于光增强杀菌EI北大核心CSCD

近红外光敏剂由于荧光成像具有光损伤小、穿透力强和空间分辨率高等优点,能显著提高光动力治疗效果。我们合成了近红外聚集诱导探针5,6-2(4′-(二苯氨酚)-[1,1′-联苯]-4-yl)吡嗪-2,3-二甲腈(DCDPP-2TPA)用于光增强杀菌。利用聚集态/固态下荧光增强的优势,DCDPP-2TPA与磁性Fe_(3)O_(4)纳米材料复合,产生更高活性氧(ROS)用于杀菌。利用SEM、TEM、XRD和荧光光谱研究了该复合材料的结构和性质,并用于大肠杆菌和金黄色葡萄球菌杀菌实验。结果表明,在光照下两种细菌的存活率为7.5%与9.0%,优于DCDPP-2TPA(10%与14%)。同时该复合材料可以方便地实现磁性分离,在光照下产生ROS后循环杀菌。     

共轭低聚物中光生分子间电荷转移态的第一性原理研究（英文）

本文用密度泛函理论研究了一种给体-受体型低聚物(2,6-二(4-甲基-1-苯并噻二唑基)-4,4-二(2-乙基己基)-二噻吩并环戊二烯)中电荷转移态的光产生机制.研究表明,当CPDTBT单体的BT基团(苯并噻二唑)偏离共轭平面大于20°时,CPDTBT二聚体在光照时可以有效地产生分子间电荷转移态.计算表明,530 nm波长的光激发只能产生分子内的电荷转移态,而370 nm短波长的光激发才能产生分子间的电荷转移态,这和实验结果是比较一致的.本文还讨论了CPDTBT低聚物中光生电荷的分离机制.     

基于酞菁钯和C60的异质结有机光敏场效应管

采用酞菁钯(PdPc)和C60两种有机半导体材料,通过真空热蒸镀法以不同的沉积顺序制备了两种不同结构的平面异质结有机光敏场效应管,并对这两种结构器件的光敏特性进行比较。在波长655 nm、光强100mW/cm2的光照条件下,结构为n+-Si/SiO2/PdPc/C60/Al(S&D)(PdPc/C60-OFET)器件的最大光暗比为2×103,光响应度为3 mA/W;而结构为n+-Si/SiO2/C60/PdPc/Al(S&D)(C60/PdPc-OFET)器件的最大光暗比为3×103,光响应度为11mA/W。实验结果表明C60/PdPc-OFET可以获得更好的光敏特性。     

硅衬底Ba1-xSrxNbyTi1-yO3薄膜光敏特性的研究

利用硅平面工艺和氩离子束镀膜技术在SiO2/Si衬底上淀积一层厚45nm的钛铌酸锶钡(Ba1-xSrxNbyTi1-yO3)薄膜，制成Al/Ba1-xSrxNbyTi1-yO3/SiO2/Si结构平面型薄膜电阻器。测试了该薄膜电阻器的吸收光谱，不同照度、电压下的光电流，调制光下的频率特性。实验结果表明：在钛酸钡中掺入锶(Sr)和铌(Nb)后，禁带内引入了杂质能级，钛铌酸锶钡禁带宽度变为2.7eV，且可见光区域存在连续的吸收峰。该薄膜在近紫外及可见光范围内具有良好的光敏特性，其灵敏度和光电导增益较高，并且具有较好的线性光照特性。光照强度较低时，电阻器的光照特性属于单分子复合过程；光照强度较高时，电阻器的光照特性属于双分子复合过程。通过对该薄膜电阻器频率特性的测量得出：在光照度为200lx时，薄膜中光生载流子的寿命为27ms。     

基于SERS研究光动力治疗中的癌细胞损伤

光动力治疗(PDT)是一种涉及光及光敏剂(光敏药物)与分子氧结合用于诱导细胞损伤或死亡的光化学治疗方法~([1]),因对正常细胞器官损伤轻微而被广泛应用。其过程是用特定波长光照射癌变部位,使选择性聚集在癌变部位的光敏药物活化,从而引发光化学反应破坏癌细胞。表面增强拉曼光谱(SERS)作为分子振动光谱技术,具有灵敏度高、检测速度快、无损及免标记等优点。基于此,本研究设计构筑一种基于靶向细胞器的等离激元探针,用于选择性获得特定细胞器的SERS光谱,通过SERS对光动力治疗过程中的细胞损伤进行分析,为光动力治疗机制提供评价依据。     

静电场诱导的分子双光子吸收截面和光限幅性能的变化

采用时域有限差分法数值求解麦克斯韦-布洛赫方程,研究了当存在静电场时少周期脉冲激光在4,4'-二(二正丁胺基)二苯乙烯(BDBAS)分子介质中的传播过程,得到了分子的动态双光子吸收(TPA)截面并且展示了其光限幅行为. 由于静电场的存在打破了BDBAS分子的对称性,因此激光在传播过程中,其频谱同时出现了偶次谐波和奇次谐波. 随着静电场强度的增加,分子的动态TPA截面增大,同时光限幅效应更为明显.     

基于并五苯/酞菁铅异质结的近红外光敏有机场效应管(英文)

采用并五苯(Pentacene)和酞菁铅(PbPc)两种有机材料作为有源层,制备了异质结有机光敏场效应管。在波长为808 nm、强度为124 mW/cm2的近红外光照条件下,异质结phOFET获得最大的光暗电流比达4.4×104,栅压为-50 V时的最大光响应度为118 mA/W,比单层酞菁铅phOFET分别高出766倍和785倍。在经过120 h后,器件的最大光暗电流比和最大光响应度分别稳定于5.4×104和326 mA/W附近。由于在异质结phOFET中采用了对近红外光具有高吸收效率的酞菁铅作为光敏层,而高空穴迁移率的并五苯材料作为靠近栅介质的沟道层,光生载流子的产生与传输能力得到了有效的提高。实验结果表明,基于并五苯/酞菁铅的有机异质结应用于光敏有机场效应管的结构设计中,可以使phOFET成为一种同时具有良好光敏性及稳定性的近红外光探测器件。     

5,7''-(亚甲胺基)-二-8-羟基喹啉及其衍生物的密度泛函理论计算

在B3LYP/6-31G(d)水平上对5,7'-(亚甲胺基)-二-8-羟基喹啉及其5种衍生物进行了几何构型全优化,探讨了喹啉不同位H被吸电子基团CN及羟基O被S原子取代对分子电离势(Ip)、电子亲和势(EA)、电荷转移、前线轨道能量和电子光谱等性质的影响.用含时密度泛函理论(TD-DFT)计算了分子在气相及液相的吸收光谱,计算结果与实验值基本符合.取代基对5,7'-(亚甲胺基)-二-8-羟基喹啉锌分子的性质有较大影响.电子亲和势计算表明,该类化合物的电子亲和势较大,都是较好的电子传输材料.     

西佛碱型液晶化合物相变过程中分子排列方式变化的拉曼光谱研究

用变温拉曼光谱对相变过程的研究表明,液晶化合物的初始晶态与熔融后缓慢降温得到的晶态并不吻合,两个状态下分子尾链的构象及刚性核部分的构象不同导致分子的聚集状态不同。西佛碱型液晶化合物VO10相变过程中,在晶态到液晶态相转变过程中,烷氧基尾链链内构象发生突变,同时有序性降低,刚性核部分两个苯环之间的二面角在相变点时发生明显变化,二面角加大。     

Resonance Raman intensity analysisof the excited‐state photochemical dynamicsof dimethyl 1,3‐dithiole‐2‐thione‐4,5‐dicarboxylate in the A‐band absorption

Dimethyl 1,3‐dithiole‐2‐thione‐4,5‐dicarboxylate (DDTD) was synthesized and characterized using NMR, Fourier transform (FT)‐Raman, Fourier transform‐infrared (FT‐IR) and UV spectroscopies. Resonance Raman spectra (RRs) were obtained with 341.5, 354.7 and 368.9 nm excitation wavelengths and density functional calculations were carried out to elucidate the π (S C S) →π* (S C S) electronic transitions and the RRs of DDTD in cyclohexane solution. The RRs indicate that the Franck–Condon region photo dynamics have a multidimensional character with motion predominantly along the CS stretch and the C S symmetric stretch modes in the five‐member heterocycle. A preliminary resonance Raman intensity analysis was carried out and the results for DDTD were compared with previously reported results for 1,3‐dithiole‐2‐thione (DTT). Differences and similarities of the spectra in terms of molecular symmetry and electron density are also discussed. Copyright © 2010 John Wiley & Sons, Ltd.     

Molecular structure of alkali metal 4‐nitrobenzoates

The influence of lithium, sodium, potassium, rubidium, and cesium on the electronic system of the 4‐nitrobenzoic acid molecule was studied. The vibrational (FT‐IR, FT‐Raman) and NMR (¹H and ¹³C) spectra for 4‐nitrobenzoic acid salts of alkali metals were recorded. The assignment of vibrational spectra was done. Characteristic shifts of band wavenumbers and change in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 4‐nitrobenzoates and ionic potential, electronegativity, atomic mass, and affinity of metals were found. The chemical shifts of protons and carbons (¹H, ¹³C NMR) in the series of studied alkali metal 4‐nitrobenzoates were observed too. Optimized geometrical structures of studied compounds were calculated by HF, B3PW91, B3LYP methods using 6‐311++G** basis set. The theoretical IR, Raman, and NMR spectra were obtained. The theoretical vibrational spectra were interpreted by means of potential energy distributions (PEDs) using VEDA 3 program. The calculated parameters were compared to experimental characteristic of studied compounds. Copyright © 2007 John Wiley & Sons, Ltd.     

FT‐IR and FT‐Raman investigations of the chemosensing material para‐hexafluoroisopropanol aniline

As an important chemosensing material involving hexafluoroisopropanol (HFIP) for detecting nerve agents, para‐HFIP aniline (p‐HFIPA) has been firstly synthesized through a new reaction approach and then characterized by nuclear magnetic resonance and mass spectrometry experiments. Fourier transform infrared absorption spectroscopy (FT‐IR) and FT‐Raman spectra of p‐HFIPA have been obtained in the regions of 4000–500 and 4000–200 cm⁻¹, respectively. Detailed identifications of its fundamental vibrational bands have been given for the first time. Moreover, p‐HFIPA has been optimized and vibrational wavenumber analysis can be subsequently performed via density functional theory (DFT) approach in order to assist these identifications in the experimental FT‐IR and FT‐Raman spectra. The present experimental FT‐IR and FT‐Raman spectra of p‐HFIPA are in good agreement with theoretical FT‐IR and FT‐Raman spectra. Copyright © 2009 John Wiley & Sons, Ltd.     

Experimental and theoretical FT‐IR and FT‐Raman spectroscopic analysis of N1‐methyl‐2‐chloroaniline

In this work, the experimental and theoretical vibrational spectra of N1‐methyl‐2‐chloroaniline (C₇H₈NCl) were studied. FT‐IR and FT‐Raman spectra of the title molecule in the liquid phase were recorded in the region 4000–400 cm^?1 and 3500–50 cm^?1, respectively. The structural and spectroscopic data of the molecule in the ground state were calculated by using density functional method (B3LYP) with the 6‐311++G(d,p) basis set. The vibrational frequencies were calculated and scaled values were compared with experimental FT‐IR and FT‐Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. ¹³C and ¹H NMR chemical shifts results were compared with the experimental values. The optimized geometric parameters (bond lengths and bond angles) were given and are in agreement with the corresponding experimental values of aniline and p‐methyl aniline. Copyright © 2008 John Wiley & Sons, Ltd.     

Identification of berberine in ancient and historical textiles by surface‐enhanced Raman scattering

The highly fluorescent natural dye berberine can be easily identified in microscopic textile samples by surface‐enhanced Raman spectroscopy employing citrate‐reduced Ag colloid. The ordinary Raman (OR) and SERS spectra of berberine are presented and discussed in the light of a DFT calculation. Using FT‐Raman and FT‐SERS we could reliably compare relative intensity shifts and investigate the adsorption geometry of berberine on Ag nanoparticles. The significant enhancement in the FT‐SERS spectrum of the out‐of‐plane ring system bending deformation mode at 729 cm⁻¹ relative to a group of in‐plane vibrations at around 1500 cm⁻¹ was interpreted as evidence of a ‘flat‐on’ adsorption geometry. SERS was successfully used to identify berberine in silk fiber samples coated with colloidal Ag following a pretreatment with HCl vapor. The SERS method allowed us to detect berberine in a microscopic sample of a single silk fiber from a severely degraded and soiled 17th Century Chinese textile fragment. Copyright © 2007 John Wiley & Sons, Ltd.     

Molecular structure,spectroscopic (FTIR,FTIR gas phase,FT‐Raman) first‐order hyperpolarizability and HOMO–LUMO analysis of 4‐methoxy‐2‐methyl benzoic acid

Vibrational spectral analysis was carried out for 4‐methoxy‐2‐methyl benzoic acid (4M2MBA) by using Fourier transform infrared (FT‐IR) (solid, gas phase) and FT‐Raman spectroscopy in the range of 400–4000 and 10–3500 cm⁻¹ respectively. The effects of molecular association through O H···O hydrogen bonding have been described by the single dimer structure. The theoretical computational density functional theory (DFT) and Hatree‐Fock (HF) method were performed at 6–311++G(d,p) levels to derive the equilibrium geometry, vibrational wavenumbers, infrared intensities and Raman scattering activities. The scaled theoretical wavenumbers were also shown to be in good agreement with experimental data. The first‐order hyperpolarizability (β₀) of this novel molecular system and related properties (β, α₀ and Δα) of 4M2MBA are calculated using the B3LYP/cc‐pvdz basis set, based on the finite‐field approach. A detailed interpretation of the infrared and Raman spectra of 4M2MBA is reported. The theoretical spectrograms for FT‐IR and FT‐Raman spectra of the title molecule were also constructed and compared with the experimental one. Copyright © 2010 John Wiley & Sons, Ltd.     

Minerals from Macedonia. XXII. Laser‐induced fluorescence bands in the FT‐Raman spectrum of almandine mineral

Two strong bands centered at 446 and 607 cm⁻¹ have been observed in the FT‐Raman spectrum of almandine [Fe₃Al₂(SiO₄)₃] excited with 1064 nm, which were completely absent in the corresponding dispersive Raman spectra obtained using 488, 514.5 and 532 nm excitation. Furthermore, the mentioned strong bands have not been registered in the anti‐Stokes side of the FT‐Raman spectrum, and were therefore assigned to laser‐induced fluorescence bands. Their appearance is related to the presence of rare‐earth element traces as impurities in the almandine sample. Additionally, the FT‐Raman (and dispersive Raman) spectrum of the isomorphous spessartine [Mn₃Al₂(SiO₄)₃] mineral has been introduced, which did not show the presence of these fluorescence emission bands. The purity of the minerals was confirmed by study of their powder X‐ray diffraction (PXRD) patterns. Copyright © 2008 John Wiley & Sons, Ltd.     

Synthesis and Raman spectroscopic investigation of a new self‐assembly monolayer material 4‐[N‐phenyl‐N‐(3‐methylphenyl)‐amino]‐benzoic acid for organic light‐emitting devices

We have synthesized 4‐[N‐phenyl‐N‐(3‐methylphenyl)‐amino]‐benzoic acid (4‐[PBA]) and investigated its molecular vibrations by infrared and Raman spectroscopies as well as by calculations based on the density functional theory (DFT) approach. The Fourier transform (FT) Raman, dispersive Raman and FT‐IR spectra of 4‐[PBA] were recorded in the solid phase. We analyzed the optimized geometric structure and energies of 4‐[PBA] in the ground state. Stability of the molecule arising from hyperconjugative interactions and charge delocalization was studied using natural bond orbital analysis. The results show that change in electron density in the σ* and π* antibonding orbitals and E₂ energies confirm the occurrence of intramolecular charge transfer within the molecule. Theoretical calculations were performed at the DFT level using the Gaussian 09 program. Selected experimental bands were assigned and characterized on the basis of the scaled theoretical wavenumbers by their total energy distribution. The good agreement between the experimental and theoretical spectra allowed positive assignment of the observed vibrational absorption bands. Finally, the calculation results were applied to simulate the Raman and IR spectra of the title compound, which show agreement with the observed spectra. Copyright © 2011 John Wiley & Sons, Ltd.     

Combined 1H NMR and DFT study of the solvent effects on the iron pentacarbonyl‐catalyzed photo‐assisted isomerization of allyl alcohol

The relative rates of iron pentacarbonyl‐catalyzed photo‐induced isomerization of allyl alcohol to propanal in various solvents have been measured using ¹H NMR spectroscopy. The reactions were run in linear and cyclic alkanes, alcohols, and amines in order to investigate solvent effects on the isomerization mechanism upon ultraviolet irradiation. The isomerization was efficient in nonane, hexane, cyclohexane, and benzene. The isomerization was very slow or completely suppressed in ethanol, propanol, isopropanol, triethylamine, and pyridine. Density functional theory calculations predicted thermodynamically favorable (ΔG^o < 0) formation of Fe(CO)₄–solvent compounds in the suppressing alcohol/amine solvents and unfavorable (ΔG^o > 0) formation in the hydrocarbon solvents. The strong solvent ligation likely prevents formation of Fe(CO)₃●(η²‐alkene) necessary for isomerization. Copyright © 2013 John Wiley & Sons, Ltd.