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Chemical Research in Chinese Universities 2002年第4期18卷 433-437页

作者： Yukihiro Ozaki DepartmentofChemistry SchoolofScienceandTechnologyKwansei-GakuinUniversity

The orientation and structural characterization of the ultrathin film of azobenzene-containing amphiphilic compound, C_ 12AzoNaph(1,4)C_6N +Br -, were studied in the present study. The compound can form a stable monolayer with sodium dextrin sulfate(SDS) by means of electrostatic interaction. Fourier-transform infrared(FT-IR) and near-infrared surface-enhanced Raman scattering(NIR-SERS) spectroscopies were used to study the orientation and characterize the structure of the Langmuir-Blodgett(LB) film and the dipping film. The FT-IR spectra indicate that the alkyl tail is nearly perpendicular to the substrate surface without any aggregation and adopts largely trans-zigzag conformation in the LB film. The NIR-SERS spectra demonstrate that the chromorphoric part in C_ 12AzoNaph(1,4)C_6N +Br is also nearly perpendicular to the surface of silver substrate both in the dipping film and the LB film. A new 'sandwiched system' model was designed to investigate the orientation and structural characterization of the chromophoric part in the multi-monolayer LB films on the non-SERS active substrate. The SERS mechanism of the 'sandwiched system' is discussed in the present paper.

关键词： molecular orientation LB film NIR-SERS spectroscopy

A modeling analysis of molecular orientation at interfaces by polarization-dependent sum frequency generation vibrational spectroscopy

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Chinese Journal of Catalysis 2019年第11期40卷 1655-1667页

作者： Xia Li Günther Rupprechter Institute of Materials Chemistry Technische Universitat Wien 1060 Vienna Austria

Sum frequency generation(SFG) vibrational spectroscopy has been proven an excellent tool to measure the molecular structures, symmetries and orientations at surfaces/interfaces because of its strong polarization dependence. However, a precise quantitative analysis of SFG spectral intensity and molecular orientation at interfaces must be carefully performed. In this work, we summarized the parameters and factors that are often ignored and illustrated them by evaluating studies of CO adsorption on the(111) facet of platinum(Pt) and palladium(Pd) single crystals at the gas(ultra-high vacuum, UHV)/solid interfaces and methanol(water) adsorption at the air/liquid(solid/liquid) interfaces in the presence of sodium iodide(chloride) salts. To intuitively estimate the influence of incidence angles and refractive indices on the SFG intensity, solely a defined factor of|Fyyz| was discussed, which can be individually separated from the macroscopic second-order non-linear susceptibility χ yyz^(2) term and represents the SSP intensity. Moreover, effects of refractive indices and the molecular hyperpolarizability ratio(R) were discussed in the orientational analysis of interfacial CO and methanol molecules. When IPPP/ISSP was identical, molecules with a larger R had smaller tilting angles(q) on Pt(assuming q orientation in the presence of sodium iodide salts at air/liquid and solid/liquid interfaces. This work should provide a guideline for analyzing the orientation of molecules with different R, which are adsorbed on catalysts or located at liquid interfaces involving changes of refractive indices.

关键词： Sum frequency generation spectroscopy Surface/interface Heterogeneous catalysis molecular orientation Refractive index Incidence angles molecular hyperpolarizability ratio

X-ray microscopic investigation of molecular orientation in a hole carrier thin film for organic solar cells

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Nano Research 2018年第5期11卷 2771-2782页

作者： Quentin Arnoux Benjamin Watts Sufal Swaraj Francois Rochet Ludovic Tortech Laboratoire de Chimie Physique Matiere et Rayonnement (LCPMR) UMR 7614 Sorbonne Universites UPMC Univ Paris 06 Paris F-75005 France Institut Parisien de Chimie Moleculaire (IPCM) UMR 8232 Sorbonne Universites UPMC Univ Paris 06 Paris F-75005 France Laboratoire d'Innovation en Chimie des Surfaces et Nanosciences (LICSEN) NIMBE UMR 3685 CEA Saday Gif-sur-Yvette F-91191 France Paul Scherrer Institute Villigen Psi 5232 Switzerland Synchrotron SOLEIL L'Orme des Merisiers Saint-Aubin BP 48 Gif-sur-Yvette F-91192 France

As dipyranylidenes are excellent hole carriers, applications in organic solar cells or organic light emitting diode are envisaged. In the present study, we investigate the morphology of 2,2＇,6,6＇-tetraphenyl-4,4＇-dipyranylidene （DIPO-Ph4） deposited under vacuum on a silicon nitride （Si3N4） substrate, a paradigmatic system for the study of molecular crystal/inorganic substrate interfaces. Samples with various coating ratios and different thermal treatments were prepared. The films were characterized by atomic force microscopy and scanning transmission X-ray microscopy to gain insight into material growth. The results show a change in orientation at a molecular level depending upon the evaporation conditions. We are now able to tailor an organic layer with a specific molecular orientation and a specific electronic behavior.

关键词： organic solar cells scanning transmission X-ray microscopy molecular orientation inorganic/organic interface

Influence factor analysis of field-free molecular orientation

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Chinese Physics B 2018年第3期27卷 231-237页

作者： Jing-Song Liu Qi-Yuan Cheng Da-Guang Yue Xu-Cong Zhou Qing-Tian Meng School of Physics and Electronics Shandong Normal University Ji＇ nan 250358 China

The effects of the characteristics of molecules and external fields on field-free molecular orientation are investigated through the comparison of HBr with LiH driven by the combination of a two-color laser pulse and a time-delayed THz laser pulse. It is shown that the dipole interaction has greater influence on field-free orientation than the hyperpolarizability interaction. In addition to the temperature dependence of orientation degree, the effects of the amplitudes of the two-color laser pulse and THz laser pulse, rising time, and THz laser frequency on molecular orientation are also discussed.

关键词： molecular orientation external fields LiH HBr

Probing molecular orientation at bulk heterojunctions by polarization-selective transient absorption spectroscopy

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Science China Chemistry 2021年第9期64卷 1569-1576页

作者： Cankun Zhang Yuzhe Zhang Zhiye Wang Yuming Su Zhixiang Wei Jianhui Hou Shan He Kaifeng Wu Chang He Jianqi Zhang Cheng Wang State Key Laboratory for Physical Chemistry of Solid Surfaces iChEMCollege of Chemistry and Chemical EngineeringXiamen UniversityXiamen361005China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) FuzhouChina CAS Key Laboratory of Nanosystem and Hierarchical Fabrication CAS Center for Excellence in NanosciecneNational Center for Nanoscience and TechnologyBeijing100190China State Key Laboratory of Polymer Physics and Chemistry Institute of ChemistryChinese Academy of SciencesBeijing100190China State Key Laboratory of molecular Reaction Dynamics and Dynamics Research Center for Energy and Environmental Materials Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian116023China

A bulk heterojunction in organic solar cells is where charge separation and recombination *** orientation at the interface is one of the key factors that dictate solar cell *** X-ray scattering-based methods can determine donor/acceptor domain orientations between an anisotropic phase and an isotropic fullerene-based phase,the rise of nonfullerene solar cells presents a new challenge in delineating local molecular directions at the interface between two anisotropic donor/acceptor ***,we determine interfacial molecular orientations of three high-efficiency small molecule solar cells(ZR1:Y6,B1:BO-4 Cl,and BTR:BO-4 Cl)using polarization-selective transient absorption *** polarization anisotropy of charge separation dynamics indicates an angle of~90°between ZR1 and Y6 molecules at the interface,an angle close to 0°between B1 and BO-4 Cl,and random orientations between BTR and BO-4 *** observations provide complementary information to X-ray scattering measurements and highlight polarization-selective transient absorption spectroscopy as a tool to probe interfacial structure and dynamics of key photophysical steps in energy conversion.

关键词： polarization-selective transient absorption spectroscopy bulk heterojunction organic solar cell molecular orientation

High Strength Electrospun Single Copolyacrylonitrile(coPAN)Nanofibers with Improved molecular orientation by Drawing

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Chinese Journal of Polymer Science 2021年第2期39卷 174-180,I0006页

作者： Tang-Cheng Xu Dong-Hua Han Yong-Mei Zhu Gai-Gai Duan Kun-Ming Liu Hao-Qing Hou Department of Chemistry and Chemical Engineering Jiangxi Normal UniversityNanchang 330022China Co-Innovation Center of Efficient Processing and Utilization of Forest Resources College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037China School of Metallurgical and Chemical Engineering Jiangxi University of Science and TechnologyGanzhou 341000China

High-performance carbon nanofibers are highly dependent on the performance of their precursors,especially polyacrylonitrile(PAN).In this work,the copolymer of PAN(coPAN)was synthesized for electrospinning.A self-assembling set-up was used for the stretching of single coPAN *** and Raman spectroscopies were used to characterize the chemical structure of coPAN *** electron microscopy(SEM)and atomic force microscopy(AFM)were used to monitor the morphology of single coPAN nanofibers under different drawing ***-tensile test was used to determine the mechanical properties of single coPAN *** results indicated that the drawing led to an increase in degree of molecular orientation along the fiber axis from 0.656 to 0.808,tensile strength from 304 MPa to 595 MPa,and modulus from 3.1 GPa to 12.4 *** research would provide fundamental information of high-performance electrospun coPAN nanofibers and offer opportunities for the preparation of high-performance carbon nanofibers.

关键词： Single nanofiber Electrospinning Polyacrylonitrile molecular orientation Mechanical property

Electronic states and molecular orientation of ITIC film

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Chinese Physics B 2018年第8期27卷 665-669页

作者： Ying-Ying Du De-Qu Lin Guang-Hua Chen Xin-Yuan Bail Long-Xi Wang Rui Wu Jia-Ou Wang Hai-Jie Qian Hong-Nian Lil Department of Physics Zhejiang UniversityHangzhou 310027China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China

ITIC is the milestone of non-fullerene small molecule acceptors used in organic solar cells. We study the electronic states and molecular orientation of ITIC film using photoelectron spectroscopy and x-ray absorption spectroscopy. The negative integer charge transfer energy level is determined to be 4.00 ± 0.05 eV below the vacuum level, and the ionization potential is 5,75 ±0.10 eV. The molecules predominantly have the face-on orientation on inert substrates as long as the surfaces of the substrates are not too rough. These results provide the physical understanding of the high performance of ITIC-based solar ceils, which also afford implications to design more advanced photovoltaic small molecules.

关键词： electronic states molecular orientation photovoltaic small molecule photoelectron spectroscopy,XAS

Field-free molecular orientation induced by combined femtosecond single-and dual-color laser pulses: The role of delay time and quantum interference

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Chinese Physics B 2014年第1期23卷 201-205页

作者：秦朝朝贾光瑞张现周刘玉芳龙金友张冰 Department of Physics Henan Normal University Xinxiang 453007 China State Key Laboratory of Magnetic Resonance and Atomic and molecular Physics Wuhan Institute of Physics and MathematicsChinese Academy of Sciences Wuhan 430071 China

The coherent control of field-free molecular orientation of CO with combined femtosecond single- and dual-color laser pulses has been theoretically studied. The effect of the delay time between the femtosecond single- and dual-color laser pulses is discussed, and the physical mechanism of the enhancement of molecular orientation with pre-alignment of the molecule is investigated. It is found that the basic mechanism is based on the creation of a rotational wave packet by the femtosecond single-color laser pulse. Furthermore, we investigate the interference between multiple rotational excitation pathways following pre-alignment with femtosecond single-color laser pulse. It is shown that such interference can lead to an enhancement of the orientation of CO molecule by a factor of 1.6.

关键词： molecular orientation femtosecond dual-color laser pulse quantum interference

Density functional theory for molecular orientation of hard rod fluids in hard slits

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Chinese Physics B 2007年第8期16卷 2296-2303页

作者：曹达鹏程礼盛汪文川 Division of molecular and Materials Simulation Key Laboratory of NanomaterialsMinistry of Education Beijing University of Chemical Technology Beijing 100029 China

A density functional theory （DFT） is used to investigate molecular orientation of hard rod fluids in a hard slit. The DFT approach combines a modified fundamental measure theory （MFMT） for excluded-volume effect with the first order thermodynamics perturbation theory for chain connectivity. In the DFT approach, the intra-molecular bonding orientation function is introduced. We consider the effects of molecular length （i.e. aspect ratio of rod） and packing fraction on the orientations of hard rod fluids and flexible chains. For the flexible chains, the chain length has no significant effect while the packing fraction shows slight effect on the molecular orientation distribution. In contrast, for the hard rod fluids, the chain length determines the molecular orientation distribution, while the packing fraction has no significant effect on the molecular orientation distribution. By making a comparison between molecular orientations of the flexible chain and the hard rod fluid, we find that the molecular stiffness distinctly affects the molecular orientation. In addition, partitioning coefficient indicates that the longer rodlike molecule is more difficult to enter the confined phase, especially at low bulk packing fractions.

关键词： density functional theory rodlike chain molecular orientation flexible chain

A General Strategy to Electrospin Nanofibers with Ultrahigh molecular Chain orientation

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Engineering 2023年第10期29卷 179-187页

作者： Xian Wen Jian Xiong Zhaoyang Sun Liming Wang Jianyong Yu Xiaohong Qin Key Laboratory of Textile Science and Technology Ministry of EducationCollege of TextilesDonghua UniversityShanghai 201620China State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Donghua UniversityShanghai 201620China Innovation Center for Textile Science and Technology Donghua UniversityShanghai 201620China

The degree of polymer chain orientation is a key structural parameter that determines the mechanical and physical properties of ***,understanding and significantly tuning the orientation of fiber macromolecular chains remain ***,we propose a novel electrospinning technique that can efficiently modulate molecular chain orientation by controlling the electric *** contrast to the typical electrospinning method,this technique can piecewise control the electric field by applying high voltage to the metal ring instead of the *** from this change,a new electric field distribution can be realized,leading to a non-monotonic change in the drafting *** a result,the macromolecular chain orientation of polyethylene oxide(PEO)nanofibers was significantly improved with a recordhigh infrared dichroic *** was further confirmed by the sharp decrease in the PEO jet fineness of approximately 80%and the nanofiber diameter from 298 to 114 ***,the crystallinity can also be adjusted,with an obvious drop from 74.9%to 31.7%,which is different from the high crystallinity caused by oriented chains in common *** work guides a new perspective for the preparation of advanced electrospun nanofibers with optimal orientation–crystallinity properties,a merited feature for various applications.

关键词： molecular orientation Electrospinning Nanofibers Electric field Polyethylene oxide