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Polarization Dependence (polarization + dependence)
Selected AbstractsPolarization dependences of absorption and luminescence spectra on each crystal face of ,-quaterthiophene and ,-quinquethiophenePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2010Shin Tanaka Abstract Polarization dependence of the absorption spectra (ABS) and the luminescence spectra in ,-quaterthiophene (4T) and ,-quinquethiophene (5T) has been measured directly with near normal incident light on the ab, bc, and ca crystal planes of their thick single crystals (SCs). Vibronic excitons (Frenkel excitons) have been observed on each crystal plane of 4T and 5T. The polarizations of the ABS are consistent with the prediction obtained from the MOPAC calculations of the transition dipole moment directions of the molecules in the SCs. Excited electron relaxes to the lowest excited state which is composed of the LUMO states. [source] X-ray birefringence and dichroism obtained from magnetic materialsJOURNAL OF SYNCHROTRON RADIATION, Issue 4 2001S. W. Lovesey In the past decade, synchrotron radiation has triggered a surge in studies of the polarization dependence of X-ray beams passing through non-isotropic materials. A vast range of experimental results concerning polarization-dependent absorption (dichroism) and dispersion (birefringence, for example) are available from materials which are either magnetic or exhibit preferred directions due to the local atomic environment. This article aims to bring together the diversity of modern experiments in this field with established methods of optical calculus, in a way that highlights the simplicity of the underlying physics. A useful framework is formed when observable quantities, in the X-ray case, are related to atomic variables of the sample material. Atomic descriptions of absorption spectra with various levels of complexity are considered, and some well documented sum-rules are encountered. The framework is the most general allowed within the electric dipole approximation. By way of illustration, dichroic X-ray absorption by two materials with highly anisotropic properties and magnetic ions with different valence shells are considered; namely, a 3d -transition ion in ferrous niobate, and a lanthanide ion in dysprosium borocarbide. Both materials display interesting magnetic properties that are challenging to interpret at an atomic level of detail, and it is shown how absorption experiments can contribute to resolving some issues. [source] Theory of resonant X-ray emission spectroscopyJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2001A. Kotani A short review is presented of recent topics in resonant X-ray emission spectroscopy (RXES), especially of the polarization dependence of RXES in d and f electron systems. Polarization-dependent RXES provides important information on the symmetry of electronic states. A scattering-angle dependence in the fluorescence yield of rare-earth metals, RXES in polarized and depolarized configurations of TiO2, and the magnetic circular dichroism in RXES of ferromagnetic systems are discussed together with typical experimental data. [source] Hydroxil ions in scheelite type molybdates and tungstatesPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 3 2007L. Kovács Abstract The presence of hydroxil ions has been detected for the first time in as-grown scheelite type crystals. A number of stretching vibrational bands were observed in PbMoO4 and BaWO4 crystals at 8 K, while only very weak OH, absorption was found in CaMoO4, SrMoO4 and SrWO4 in the 3200,3600 cm,1 wavenumber range. The anharmonicity of the stretching modes for all bands in PbMoO4 and BaWO4 was found to be in agreement with that observed in other oxides. The model of weak coupling to a single phonon band was used to interpret the temperature dependence of the OH, band positions and halfwidths. Strong polarization dependence was observed for the OH, vibrations in both crystals indicating that the O,H dipoles incorporate the lattice along different O,O bonds. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | ||||||||||