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Angle Dependence (angle + dependence)
Selected AbstractsEffect of the molecular weight and architecture on the size and glass transition of arborescent polyisobutylenesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 5 2006Judit E. Puskas Abstract This article discusses the characterization of arborescent (hyperbranched) polyisobutylenes (arb-PIBs) by size exclusion chromatography and differential scanning calorimetry, in comparison with linear PIB standards. The radius of gyration (,r,1/2 = Rz), measured from the angle dependence of light scattering of high-molecular-weight arb-PIBs, was significantly larger than the hydrodynamic radius (Rh) from size exclusion chromatography/viscometry, and the Rh values were significantly smaller than Rh of linear PIBs. The glass-transition temperature of arb-PIBs having a branch molecular weight higher than the critical entanglement molecular weight was dependent on both the total number-average molecular weight and BR up to BR , 15. A modified Fox,Flory equation is proposed to describe the effect of architecture on the thermal transition. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1770,1776, 2006 [source] Polarization coherent anti-stokes Raman scattering using noisy lightJOURNAL OF RAMAN SPECTROSCOPY, Issue 1 2007Lindsay R. Weisel Abstract Several polarization studies on the noisy light version of coherent anti-Stokes Raman scattering (CARS) exist in the literature. However, the full advantages of polarization CARS (P-CARS), which are so useful in conventional and short-pulse CARS methods, have not yet been exploited in the noisy light version. This work presents experimental realization of fully functional P-CARS using noisy light. Several examples demonstrate the advantages brought by P-CARS. This includes the ,classic' example of benzene in carbon tetrachloride. Also presented are the carbon,carbon double bond stretches in acrylonitrile and 1-hexene. An interesting, and not fully understood, detection polarization angle dependence is discussed. Applications to an m -xylene/benzene mixture and an alkaline solution of the amino acid phenylalanine are presented. Copyright © 2006 John Wiley & Sons, Ltd. [source] 1H chemical shifts in NMR: Part 23,, the effect of dimethyl sulphoxide versus chloroform solvent on 1H chemical shiftsMAGNETIC RESONANCE IN CHEMISTRY, Issue 5 2006Raymond J. Abraham Abstract The 1H chemical shifts of 124 compounds containing a variety of functional groups have been recorded in CDCl3 and DMSO- d6 (henceforth DMSO) solvents. The 1H solvent shift ,, = ,(DMSO) , ,(CDCl3) varies from ,0.3 to +4.6 ppm. This solvent shift can be accurately predicted (rms error 0.05 ppm) using the charge model of ,, ,, , and long-range contributions. The labile protons of alcohols, acids, amines and amides give both, the largest solvent shifts and the largest errors. The contributions for the various groups are tabulated and it is shown that for H.C.C.X ,-effects (X = OH, NH, O, NH.CO) there is a dihedral angle dependence of the ,-effect. The group contributions are discussed in terms of the possible solvent,solute interactions. For protic hydrogens, hydrogen bonding is the dominant interaction, but for the remaining protons solvent anisotropy and electric field effects appear to be the major factors. Copyright © 2006 John Wiley & Sons, Ltd. [source] Spin-decoherence effects on the pumped spin-dependent transport through a quantum dotPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 6 2009Hui Pan Abstract We theoretically study the spin-decoherence effects on the pumped spin-polarized current through a quantum dot subject to a rotating magnetic field and coupled to two ferromagnetic electrodes. The dependence of the current on the magnetic moment orientation angle of the two leads is greatly influenced by the spin pump and the spin decoherence. The spin pump destroys the normal spin-valve effects, and the spin decoherence makes the current exhibiting a quite complicated angle dependence. These distinct transport behaviors can be used as electrical schemes for detection of electron spin resonance and spin decoherence. Moreover, the current is closely related to the magnetic Rabi frequency and the detuning, in which the spin decoherence also plays an important role, and thus the pumped spin-polarized current can be used as a sensitive tool to measure these pumping parameters. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The maximal axial parameters in equivalent parametrizations of high symmetry crystal-field HamiltoniansPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2007Jacek Mulak The cover picture represents a fingerprint of crystal-field parametrization, that is a map of the normalized crystal-field parameter B40 for the Pr3+ ion in Pr2CuO4 of C4v point symmetry according to the reference frame orientation (based on the data by Riou et al. [2]). This map is equivalent to the angle dependence of the k = 4 component of the crystal-field Hamiltonian. The contour lines are the equipotential lines. The picture relates to the work by Jacek Mulak, Maciej Mulak, and Ryszard Gonczarek [1]. The first author is a graduate in Chemistry (Wroclaw University of Technology, 1962) and Mathematics (University of Wroclaw, 1968), now holding the position of a professor at the Institute of Low Temperature and Structure Research, Polish Academy of Sciences in Wroclaw, Poland. He specializes in the crystal-field theory and its application to magnetism and spectroscopy. He embarked on his scientific career as an assistant professor to Professor W,odzimierz Trzebiatowski (1906,1982). The paper is then a tribute to Professor W,odzimierz Trzebiatowski, the founder of the physico-chemical school at Wroclaw's Academic Center. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] A Spectroscopic Study of the Reduction of Geometrically Restrained ViologensCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2007Andrew Abstract A small series of N,N,-dimethyl-4,4,-bipyridinium dication derivatives (commonly known as viologens) has been synthesized and fully characterized; a short dialkoxy tether attached at the 3,3,-positions is used to alter the central dihedral angle. These angles were determined by both single-crystal X-ray diffraction and by computational studies made for the dication, radical cation, and neutral species in a solvent reservoir. The dihedral angle derived for the dication controls the first reduction potential, whereas the geometry of the resultant ,-radical cation determines the magnitude of the second reduction potential. The optical absorption spectra recorded for the various species, and especially those of the radical cations, and the EPR spectral parameters of the ,-radical cations also depend on the molecular geometry. In particular, the central dihedral angle influences the spin density distribution around the aromatic nucleus and, by way of comparison to the parent viologen, it has been possible to resolve the angle dependence from the inherent inductive effect of the strap. These results are considered in terms of the degree of electronic communication between the two aromatic rings, as controlled by the length of the tether. [source] | ||||||||||