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1.
Toshihiro Mino Yuika Saito Hiroyuki Yoshida Satoshi Kawata Prabhat Verma 《Journal of Raman spectroscopy : JRS》2012,43(12):2029-2034
Polarization‐dependent Raman microscopy is a powerful technique to perform both structural and chemical analyses with submicron spatial resolution. In conventional Raman microscopy, the polarization measurements are limited only in the direction parallel to the sample plane. In this work, we overcome the limit of conventional measurements by controlling the incident polarization by a spatially modulated waveplate. In this method, the polarization perpendicular to the sample surface (z‐polarization) can be detected together with the parallel polarization (xy‐polarization). Because of this unique polarization control, our Raman microscope has the ability to image the molecular orientation, together with the molecular analysis. Here, we have investigated thin films of pentacene molecules that are widely studied as an organic semiconductor material. The orientations of pentacene molecules are imaged with a spatial resolution of 300 nm. Our results clearly indicate that the lamellar grains show the lower tilt angles compared to the neighboring islands, which has not been proved in conventional methods. The substrate effects and the thickness dependence of the film are also studied. These results provide knowledge about the relationship between the devise performance and the film structures, which is indispensable for future device exploitations. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
2.
Philippe Colomban Hung Manh Dinh Aurlie Tourni Vincent Jauzein 《Journal of Raman spectroscopy : JRS》2012,43(8):1042-1048
The comparison of the low wavenumber of polarized Raman spectra (50–300 cm–1) from Bombyx mori (fresh cocoons fibres, hand‐stretched ‘Crins de Florence’ strings from the gland content, dried gland, regenerated silk films) and Nephila madagascarensis silks reveals the high polarisation of fibre modes and the absence of polarisation for dried gland and regenerated silk films. This is consistent with X‐ray diffraction measurements. The orientation of the fibroin/spidroin chains is due to the stretching during production, as for advanced synthetic fibres. The bandwidth of the ‘ordered chains’ signature is almost the same for the different fibres. However, the degree of polarisation seems to be higher in the case of spider fibre. The huge bandwidth of low wavenumber components of regenerated films indicates high disorder. Measurements along the fibre point out conformation changes with a periodicity (~20 mm) related to the silkworm head motion during the fabrication of the cocoon. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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4.
Formation of silk fibroin nanoparticles in water-miscible organic solvent and their characterization 总被引:2,自引:0,他引:2
Yu-Qing Zhang Wei-De Shen Ru-Li Xiang Lan-Jian Zhuge Wei-Jian Gao Wen-Bao Wang 《Journal of nanoparticle research》2007,9(5):885-900
When Silk fibre derived from Bombyx mori, a native biopolymer, was dissolved in highly concentrated neutral salts such as CaCl2, the regenerated liquid silk, a gradually degraded peptide mixture of silk fibroin, could be obtained. The silk fibroin nanoparticles
were prepared rapidly from the liquid silk by using water-miscible protonic and polar aprotonic organic solvents. The nanoparticles
are insoluble but well dispersed and stable in aqueous solution and are globular particles with a range of 35–125 nm in diameter
by means of TEM, SEM, AFM and laser sizer. Over one half of the ɛ-amino groups exist around the protein nanoparticles by using
a trinitrobenzenesulfonic acid (TNBS) method. Raman spectra shows the tyrosine residues on the surface of the globules are
more exposed than those on native silk fibers. The crystalline polymorph and conformation transition of the silk nanoparticles
from random-coil and α-helix form (Silk I) into anti-parallel β-sheet form (Silk II) are investigated in detail by using infrared,
fluorescence and Raman spectroscopy, DSC, 13C CP-MAS NMR and electron diffraction. X-ray diffraction of the silk nanoparticles shows that the nanoparticles crystallinity
is about four fifths of the native fiber. Our results indicate that the degraded peptide chains of the regenerated silk is
gathered homogeneously or heterogeneously to form a looser globular structure in aqueous solution. When introduced into excessive
organic solvent, the looser globules of the liquid silk are rapidly dispersed and simultaneously dehydrated internally and
externally, resulting in the further chain–chain contact, arrangement of those hydrophobic domains inside the globules and
final formation of crystalline silk nanoparticles with β-sheet configuration. The morphology and size of the nanoparticles
are relative to the kinds, properties and even molecular structures of organic solvents, and more significantly to the looser
globular substructure of the degraded silk fibroin in aqueous solution. It is possible that the silk protein nanoparticles
are potentially useful in biomaterials such as cosmetics, anti-UV skincare products, industrial materials and surface improving
materials, especially in enzyme/drug delivery system as vehicle. 相似文献
5.
根据弹性理论和多晶膜的屈服强度公式,计算了附着在基体上体心立方多晶薄膜中不同取向晶粒中的应变能密度.结果表明:1)在屈服之前,对Fe和Ta两种薄膜,4个最小的应变能密度对应的晶粒取向依次为(100),(510),(410)和(511);对Cr,Mo,Nb和V四种薄膜,4个最小的应变能密度对应的晶粒取向依次为(111),(332),(322)和(221);对W膜,应变能密度与晶粒取向无关.2)在屈服的体心立方多晶膜中,4个最小的应变能密度对应的晶粒取向依次为(100),(111),(110)和(411).从
关键词:
体心立方多晶薄膜
晶粒取向
应变能密度
织构 相似文献
6.
Coir/silk fiber-reinforced polypropylene (PP) based unidirectional composites (40 wt.%) were manufactured by compression molding. Coir/silk fibers and PP sheets were treated with ultraviolet radiation at different intensities and then composites were fabricated. It was found that mechanical properties of irradiated silk/irradiated PP composites were found to increase significantly compared to the untreated ones and even higher than that of irradiated coir/irradiated PP composites. Soil degradation tests indicated that irradiated coir/irradiated PP composites significantly lost much of its mechanical properties, but irradiated silk/irradiated PP composites retained their strength of its original integrity. Scanning electron microscopy and water uptake of both types of composites were also investigated. 相似文献
7.
Florian Latteyer Sabine Savu Heiko Peisert Thomas Chass 《Journal of Raman spectroscopy : JRS》2012,43(9):1227-1236
This work presents an investigation of films prepared by doctor blade casting, the formation of self‐assembled microstructures of a liquid crystalline phthalocyanine with highly oriented molecules. Raman Spectroscopy in combination with atomic force microscopy is applied to study the structures within the films. By keeping the substrate at room temperature or at 353 K during coating, different geometric structures namely rods and islands form. Rod‐like structures are growing in coating direction, whereas directional growth of the islands is not observed. The distribution of the rod lengths varies widely, whereas the width appears more uniform. Annealing of the samples shows a different behavior of the two textures. Islands tend to melt, and rods smooth their structural form, which is extracted from Raman imaging in combination with atomic force microscopy. Additionally, Raman imaging gives insight into laterally different relative crystallinity. These observations are discussed in the context of the molecular orientation as probed by polarized Raman spectroscopy. These polarized Raman spectra indicate azimuthal alignment of the molecules within the rods (edge on alignment). This alignment occurs along and also perpendicular to the growth direction. In contrast to the alignment in the rods, the molecules inside the islands occurring at higher temperature do not show preferential molecular orientation. After annealing, no preferential molecular orientation is observed in rods because of the loss of anisotropy, too. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
9.
Leonardo Puppulin Masaya Kotaki Morimasa Nakamura Daisuke Iba Ichiro Moriwaki Giuseppe Pezzotti 《Journal of Raman spectroscopy : JRS》2012,43(12):1957-1963
The orientation dependence in space of Raman‐active vibrations in the hexagonal structure of polyoxymethylene (POM) is discussed in terms of Raman tensor elements as intrinsic physical parameters of the lattice. The variation of polarized intensity for the A1 and the E1 vibrational modes with respect to the POM molecular orientation is systematically studied, from both theoretical and experimental viewpoints, according to the symmetry assignments of each vibrational mode. A set of working equations including the Raman selection rules associated with the A1 and the E1 modes and the orientation distribution function are explicitly formulated and validated by means of a least‐square fitting procedure on experimental data. In addition, an approach based on the introduction of orientation distribution functions is applied to quantitatively assess and compare on a statistical base the molecular orientation of two different types of electrospun POM nanofibers. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
10.
Jun Zhang PingHeng Tan WeiJie Zhao Jun Lu JianHua Zhao 《Journal of Raman spectroscopy : JRS》2011,42(6):1388-1391
The growth and characterization of high‐quality ultrathin Fe3O4 films on semiconductor substrates is a key step for spintronic devices. A stable, single‐crystalline ultrathin Fe3O4 film on GaAs(001) substrate is obtained by post‐growth annealing of epitaxial Fe film with thicknesses of 5 and 12 nm in air. Raman spectroscopy shows a high ability to convincingly characterize the stoichiometry, epitaxial orientation and strain of such ultrathin Fe3O4 films. Polarized Raman spectroscopy confirms the unit cell of Fe3O4 films is rotated by 45° to match that of the Fe (001) layer on GaAs, which results in a built‐in strain of − 3.5% in Fe3O4 films. The phonon strain‐shift coefficient(−126 cm−1) of the A1g mode is proposed to probe strain effect and strain relaxation of thin Fe3O4 films on substrates. It can be used to identify whether the Fe layer is fully oxidized to Fe3O4 or not. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
11.
Z. Jurasekova C. Domingo J. V. Garcia‐Ramos S. Sanchez‐Cortes 《Journal of Raman spectroscopy : JRS》2008,39(10):1309-1312
Luteolin and apigenin flavonoid have been detected in silk and wool fibres dyed with weld (Reseda luteola L.) through surface‐enhanced Raman scattering (SERS) measurements carried out ‘on the fibre’. For such purpose, Ag nanoparticles were produced and immobilised in situ via the laser photoreduction of a silver nitrate water solution in contact with the fibre. Control SERS spectra of pure luteolin and apigenin, as well as of mixtures of them, on analogous Ag nanoparticles were also obtained. In this work flavonoids with a similar molecular structure were identified on dyed fibres for the first time without previously hydrolysing the mordant–dye complex. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
12.
通过对聚乙烯咔唑(PVK) 掺杂三(2-苯基吡啶)铱(Ir(ppy)3)和4-二氰亚甲基-2-叔丁基-6-(1,1,7,7-四甲基久咯呢定基-9-烯基)-4H-吡喃(DCJTB),PVK 掺杂DCJTB和PVK掺杂Ir(ppy)3聚合物在成膜时高压电场作用下分子取向变化对单线态和三线态激子形成截面的研究,发现,随着成膜时电场的增强,单线态激子的形成截面在增加,而三线态激子的形成截面却减小.
关键词:
分子取向
激子形成截面
三线态
单线态 相似文献
13.
Xianguang MengYizao Wan Qunying LiJing Wang Honglin Luo 《Applied Surface Science》2011,257(24):10808-10814
Electrodeposition was employed to fabricate magnetite (Fe3O4) coated carbon fibers (MCCFs). Temperature and fiber surface pretreatment had a significant influence on the composition and morphology of Fe3O4 films. Uniform and compact Fe3O4 films were fabricated at 75 °C on both nitric acid treated and untreated carbon fibers, while the films prepared at 60 °C were continuous and rough. Microwave measurements of MCCF/paraffin composites (50 wt.% of MCCFs, pretreated carbon fibers as deposition substrates) were carried out in the 2-18 GHz frequency range. MCCFs prepared at 60 °C obtained a much higher loss factor than that prepared at 75 °C. However, the calculation results of reflection loss were very abnormal that MCCFs prepared at 60 °C almost had no absorption property. While MCCFs prepared at 75 °C exhibited a good absorption property and obtained −10 dB and −20 dB refection loss in wide matching thickness ranges (1.0-6.0 mm and 1.7-6.0 mm range, respectively). A secondary attenuation peak could also be observed when the thickness of MCCF/paraffin composite exceeded 4.0 mm. The minimum reflection loss was lower. 相似文献
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通过建立具有平面近横向各向异性场的非晶态合金薄带及膜的磁畴结构模型,利用线性化Maxwell方程组及Landau-Lifshitz方程,推出了在高频交变磁场及外加面内轴向直流磁场Hex作用下的铁磁材料的与取向相关的磁导率表达式,得到了对方位角平均的相对磁导率及阻抗的计算式,导出了磁导率与张量磁化率分量间的关系,对材料磁导率的实部及虚部随Hex的变化进行了计算,并给出了对应的磁谱图.建立的磁导率与外磁场的理论关系可将Panina及Kraus给出的理论结果统一起来.
关键词:
非晶态合金薄带及膜
取向相关磁导率
GMI效应理论与计算
近横向各向异性场 相似文献
16.
E. Rudigier J. Djordjevic B. Barcones R. Scheer 《Journal of Physics and Chemistry of Solids》2005,66(11):1954-1960
The growth of polycrystalline CuInSe2 and CuInS2 thin films from metallic precursor layers is investigated using two complementary in situ methods which give bulk sensitive (XRD) and surface sensitive (Raman) information. From the time evolution of the XRD and Raman peak intensities the phase transformation sequences and the reaction kinetics can be derived. In both cases the chalcogenization of the Cu-In precursors proceeds at the top surface. Thus, the process is at least limited by cation diffusion through the metallic precursor. However, the growth kinetics of CuInSe2 and CuInS2 films differ. While the CuInSe2 growth is limited by the reaction of binary phases, CuInS2 growth is controlled by fast diffusion which is solely restricted to the period of raising temperature during the process. 相似文献
17.
Ferydon Babaei 《Optics Communications》2008,281(11):3120-3130
The transmission and reflection spectra from a right-handed chiral sculptured zirconia thin film are calculated using the piecewise homogeneity approximation method and the Bruggeman homogenization formalism using both dispersive and non-dispersive functions for axial and non-axial states. The comparison of spectral results shows that the dispersion of the dielectric function has a considerable effect on the results. In axial excitation of cross-polarized reflectances and co-polarized transmittances the dispersion effect becomes more pronounced at wavelengths further away from the homogenization wavelength. This is also true in the case of non-axial excitation of circular transmittances, while there are considerable differences for cross-polarized reflectances where (wavelength) the first Bragg peak occurs. At wavelengths in the vicinity of the homogenization wavelength the dispersion effect of the dielectric function in RRR becomes more significant. 相似文献
18.
Osvaldo Vigil Jesús Fandiño Francisco Cruz-Gandarilla 《Journal of Physics and Chemistry of Solids》2010,71(3):404-406
The physical properties of the etched CdTe surfaces obtained during the process of formation of a p+ region on CdTe surface films using (i) a nitric/phosphoric acid mixture and (ii) a chemical Te-deposition method involving thermal annealing have been compared in this study. This study suggests the chemical-deposition method as an alternative to the chemical-etching methods for use in back-contact technology to increase the efficiency of CdTe solar cells. 相似文献
19.
Wenliang Zhu Jiliang Zhu Mingsong Wang Bo Zhu Xiaohong Zhu Giuseppe Pezzotti 《Journal of Raman spectroscopy : JRS》2012,43(9):1320-1328
A quantitative polarized Raman analysis of ferroelectric grain/domain orientation in LiSbO3 (LS‐modified) (K0.5Na0.5)NbO3 (KNN) ceramics is presented, based on the analysis of the complex orientation dependence in space of their Raman‐active modes. Complete sets of Raman tensor elements of Ag, and Eg phonon modes for orthorhombic/tetragonal structures of KNN have been determined. Through this spectroscopic algorithm, quantitative information could be extracted in terms of three Euler angles in space for KNN samples consisting of mixed phases, thus enabling quantitative visualization of the local distribution of grains/domains in the solid angle. As an application of the method, we quantitatively examined the unknown crystallographic grain orientation patterns on the surfaces of pure KNN and of KNN‐0.05LS ceramics. These two samples were useful to clarify a polymorphic phase transition from the orthorhombic to the tetragonal phase taking place in the LS‐modified KNN system. Thus, we demonstrated that polarized Raman spectroscopy is a valuable and efficient tool for nondestructive three‐dimensional assessments of grain/domain orientation in ferroelectric materials with complex polymorphic structures. We believe that the data shown here represent a typical scenario encountered in grain/domain orientation assessments of piezoelectric perovskites. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
W. Westhäuser S. Schramm J. Hoffmann C. Jooss 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(3):323-331
The insulator-metal (IM)-transition in Pr1-xCaxMnO3
(PCMO) is of particular interest because it can be induced by a
variety of external forces, such as magnetic and electric fields,
photon exposure and hydrostatic pressure. In this paper, we present
a comparative study of the IM-transition in magnetic and electric
fields for epitaxial thin films prepared by pulsed laser deposition.
The transport data as a function of applied field or temperature
give strong evidence for the presence of electronic phase
separation. However, the observed different IM-transitions in magnetic and electric fields indicate that two different areas
of spatially inhomogeneous electronic ground states in the phase diagram of PCMO are involved. 相似文献