Preferred orientations of encapsulated C60 molecules inside single wall carbon nanotubes

A systematical study of the orientational behavior of C60 molecules in single wall carbon nanotubes (SWCNTs) with different chirality and diameter has been performed by using a model of an infinite long nanotube filled with two C60 (denoted as C60-1 and C60-2) molecules. We studied the preferred orientation of the C60-1 molecule when the neighboring C60-2 molecule was fixed at the pentagon, double-bond, and hexagon orientations respectively. Our results showed that the C60-1 molecule prefers the pentagon (hexagon) orientation when the tube diameter is smaller (larger) than 1.31nm (1.36nm). For the tube diameter in between, the preferred molecular orientation of C60-1 changes from pentagon to hexagon with the increasing tube diameter when the neighboring C60-2 molecule is fixed at the pentagon or double-bond orientation. A novel vertex orientation for the C60-1 molecule has been found when the C60-2 molecule is fixed at the hexagon orientation.     

CBERS-02B星HR相机内方位元的在轨标定方法

遥感相机内方位元素的在轨标定对遥感图像的定位和测量具有重要意义.利用线阵推扫传感器构像模型,提出了一种对CBERS-02B星HR相机内方位元素进行在轨标定的方法.该方法以内方位元素和姿态角为未知参数,建立地面控制点和相应像点的共线方程组,通过解算共线方程组获得内方位元素.实验证明,用该方法对内方位元素进行在轨标定,具有...     

Orientation of stereoisomers by electromagnetic field

A magnetic orientation is shown to appear during light-induced drift of stereoisomers relative to a buffer gas. The magnetic orientation can be initiated even by linearly polarized or nonpolarized radiation.     

Nuclear orientation measurements and their contribution to our understanding of the structure of nuclei

A survey is made of new regions of nuclei, which may become accessible to nuclear orientation experiments as the on-line technique matures. Basic nuclear properties that can be investigated by means of nuclear orientation are briefly reviewed. Examples of systematic use of nuclear moments for revealing nuclear properties are given as is an example of of the combined use of low-spin nuclear orientation data and high-spin heavy-ion reaction data.     

Second-order orientation effects in light scattering by polarized atoms

A compact expression is derived for the part of the cross section for light scattering by axisymmetrically polarized atomic systems proportional to the third-rank state multipole. The effect of the second-order orientation determined by this state multipole on the polarization and angular distribution of the scattered light is studied. The polarization of the incident light can be arbitrary and is specified by the Stokes parameters. A number of orientation effects in the scattering process are shown to be induced precisely by the second-order orientation. In particular, when nonpolarized light is scattered by an oriented atom, the scattering intensity in the perpendicular direction depends on the second-order orientation alone. The second-order orientation also preserves circular dichroism in the linear polarization of the forward-and back-scattered light.     

Number of possible orientation states in ferroelastics and multiaxial ferroelectrics upon polymorphic phase transitions

The formation of orientation states upon structural phase transitions in ferroelastics and multiaxial ferroelectrics is analyzed. It is shown that the number of possible orientation states depends on the paraphase symmetry. A method for determining their number is proposed.     

Spontaneous transition of one-dimensional plasma photonic crystal's orientation in dielectric barrier discharge

A novel one-dimensional plasma photonic crystal whose crystal orientation can change spontaneously is demonstrated by using a dielectric barrier discharge with two liquid electrodes. The orientation of the plasma photonic crystal will vary from transverse to longitudinal or vary from longitudinal to transverse and then revert to longitudinal by self-adjustment, while the experimental conditions are kept fixed. The dispersion relations of these plasma photonic crystals are calculated, and the changes of photonic band diagrams during the orientation transition are studied.     

Effect of electric and magnetic fields on the orientation structure of a ferronematic liquid crystal

We analyze uniform orientation phases in soft ferronematics (suspensions of magnetic nanoparticles in nematic liquid crystals) induced by electric and magnetic fields. It is shown that the competition between the electric and magnetic fields can lead to various sequences of orientation transitions in a ferronematic depending on the energy of coupling between the director and magnetization. We obtain and analyze phase diagrams of these transitions. A sequence of re-entrant transitions in the orientation structure (angular phase-homeotropic phase-angular phase-planar phase) is predicted for a certain range of the coupling energies and electric field strengths.     

偶氮苯介晶基元取向方式对其取向稳定性影响

根据取向透射率变化研究了偶氮苯侧链液晶聚合物在不同光照功率条件下的取向,用锥光干涉法表征了侧链介晶基元的取向方向,并研究了升温对取向膜的稳定性影响.实验结果表明介晶基元的取向速度和取向度都随光照时间和光照功率增加而增加|超过一定阈值功率（20 mW/cm2）时,随着光照时间延长薄膜的透射率（取向度）反而降低.高功率光照使侧链介晶基元发生了面内和面外两种取向,面外取向使聚合物膜的透射率降低.面外倾斜取向的介晶基元不稳定,在取向未达到饱和时停止光照,倾斜取向的介晶基元容易发生解取向,而面内取向的介晶基元则能维持取向的状态.用不饱和取向的方法,在光照功率为 20 mW/cm2时,取向时间缩短为饱和取向的1/20,薄膜的取向度提高1.3倍.4 ms的一次曝光足以使聚合物膜产生可读出、稳定的面内取向,取向的结果能保持2年不发生变化.     

The hanle effect in nonuniformly doped GaAs

Spin density distribution in the GaAs/AlGaAs heterostructure was studied under steady-state optical orientation conditions. A comprehensive analysis of the dynamics and relaxation processes responsible for the steady-state nonuniformity of spin orientation was made. The acceptor impurity concentrations in various regions of nonuniformly doped gallium arsenide were determined. The concentrations were derived from the spin relaxation times measured using the optical orientation method.     

A method to predict the orientation relationship,interface planes and morphology between a crystalline precipitate and matrix: part II – application

A model based on near coincidence of diffraction intensity-weighted reciprocal lattice spots was used to study the orientation relationships between a precipitate and matrix in various alloys. The model was used to calculate the orientation relationship and interface orientations between phases including body-centred cubic, body-centred tetragonal, face-centred cubic and hexagonal close-packed crystals. Comparison of calculated results with those reported from various experimental observations demonstrate that in most cases the model can predict the orientation relationship between two phases with an accuracy of a few degrees or better. Calculation of the interface orientation was found to be very sensitive to the exact orientation relationship and therefore, in some cases, showed significant deviation from experimental observations.     

Manipulation of the overall polarization orientation in the focal volume of high numerical objectives

We propose an approach for tuning the three-dimensional polarization of a focusing subwavelength spot by a high numerical aperture objective. The incident beams are composed of a radially polarized beam, an azimuthally polarized beam, and a linearly polarized beam with three different weighting factors, respectively. A specially designed adjustable amplitude angular selector is also inserted at the back aperture of the objective for tuning the polarization azimuthally. It is shown that any desired overall polarization orientation can be obtained. We calculated the overall polarization orientation in the focal volume. It is found that the polar angle of the overall polarization orientation can be arbitrarily tuned by the combination of a radially polarized beam and a linearly polarized beam with different weighting factors, and the azimuthal angle can be tuned by rotating the orientation of the linearly polarized beam azimuthally.     

Optimization of retardance for a complete Stokes polarimeter

We present two figures of merit based on singular value decomposition, which can be used to assess the noise immunity of a complete Stokes polarimeter. These are used to optimize a polarimeter featuring a rotatable retarder and a fixed polarizer. A retardance of 132 degrees (approximately three-eighths wave) and retarder orientation angles of +/-51.7 degrees and +/-15.1 degrees are found to be optimal when four measurements are used. Use of this retardance affords a factor-of-1.5 improvement in signal-to-noise ratio over systems employing a quarter-wave plate. A geometric means of visualizing the optimization process is discussed, and the advantages of the use of additional measurements are investigated. No advantage of using retarder orientation angles spaced uniformly through 360 degrees is found over repeated measurements made at the four retarder orientation angles.     

Estimation of molecular orientations in disordered samples by a proton-NMR-based method

We introduce a procedure on the basis of proton nuclear magnetic resonance (NMR) for investigation of the orientation state of disordered samples like amorphous or nematic polymers. Advantageous features of this method are the following: (i) disorder of the sample is not a problem (other than in the case of X-ray); (ii) the method works faster than multidimensional NMR techniques; (iii) this procedure can be implemented also at more simple and inexpensive NMR spectrometers; and (iv) for the data evaluation it will be not necessary to know the molecular geometry. The latter is possible by introducing the expressions “relative orientation distribution” and “relative orientation degree” which characterize the difference of the orientation of the current sample in comparison to a reference sample. Contrary to the absolute orientation degrees the relative ones are easily available from wide-line proton NMR spectra. The method is demonstrated by applying it to monitor the qualitatively different behavior of the director fields of two liquid-crystalline polymer samples with different molecular weights which are exposed to a suddenly switched magnetic field. A temporary asymmetry of the orientation distribution could be detected and quantified.     

Low frictional property of copper oxide thin films optimised using a combinatorial sputter coating system

A combinatorial sputter coating system has been developed that can optimize the crystal preferred orientation of coating films. With this system, it is possible to synthesize various kinds of coatings whilst precisely controlling conditions such as the sputter gas, the gas pressure, the gas partial pressure, the r.f. power, the substrate temperature, the distance between the substrate and target, etc. In this way, we successfully synthesized copper oxide coatings with different crystal preferred orientations, and low frictional property was obtained by optimizing the crystal preferred orientation.     

Isomeric orientation by two-photon excitation: a theoretical study

I develop the theory of molecular orientation induced by two-photon isomerization. Phenomenologically, two-photon isomeric orientational hole burning and reorientation induce molecular orientation while rotational diffusion tends to randomize it. Using the formalism of Legendre polynomials solves the general equations of the theory, and analytical solutions are derived for actual physical cases at the early time evolution and the steady state of two-photon excitation. The theory explains the observed results of two-photon molecular orientation, and predicts additional experiments in this direction. The isomerization parameters and the movement of the isomers during polarized two-photon excitation can be quantified by the analytical theory. A theoretical study on the creation of molecular orientation by competing orientational Kerr effect and two-photon orientation is also presented.     

Josephson effect in superconducting hybrid S/F structures with parallel and antiparallel magnetizations of the ferromagnetic layers

The Josephson effect in S-MB-S, S/F-MB-S, and S/F-MB-F′/S superconducting hybrid structures with the parallel or antiparallel orientation of exchange fields in the layers of metal ferromagnets (F and F′) and in the magnetic barrier (MB) with arbitrary transparency has been investigated. It has been shown that the properties of the studied structures depend strongly on the orientation of the exchange fields: the exchange-field-induced stimulation of the critical current is possible for one orientation, whereas the critical current is suppressed at the opposite orientation of the exchange fields. A change in the orientation of the exchange fields can lead to the switching of the Josephson structures between 0 and π states. The effect of the pair-breaking mechanisms on the Josephson effect and on the spectrum of the Andreev levels in the S-MB-S structures has been analyzed. The results indicate the possibility of stimulating the critical current by the external magnetic field in the S-MB-S structures with thin-film superconducting banks.     

The characterization of molecular orientation in PVC with emphasis on the use of Raman spectroscopy

A comparison is given of various methods for studying orientation in polymers, with particular reference to PVC. The Raman method and its application to PVC are described in more detail. The results of a study on PVC samples containing 0—20 pph of dioctyl sebacate plasticizer uniaxially drawn at various temperatures in the range 0 to 90°C are summarized. In this work the orientation of the crystalline regions was studied. More recent investigations are briefly discussed in which the orientation of short all-trans noncrystalline syndiotactic segments is investigated and in which Young's modulus of oriented samples is measured for correlation with the Raman data.     

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

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.     

Molecular reorientation in collisions of OH + Ar

Orientational effects in rotationally elastic collisions of OH with Ar were studied in a crossed molecular beam setup. A static electric field was applied to orient the molecules before the collision. After the collision the orientation was measured by using a narrow-band laser system to probe the Stark-split states corresponding to different orientations. Differential and integral cross sections for reorientation of the molecular axis have been determined as a function of the initial orientation. The cross section for reorientation by one quantum is 25 A2 with a preference for O-end collisions.