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Line Shifts (line + shift)
Selected AbstractsLuminescence of Nanocrystalline Erbium-Doped YttriaADVANCED FUNCTIONAL MATERIALS, Issue 5 2009Yuanbing Mao Abstract In this paper, the luminescence, including photoluminescence, upconversion and cathodoluminescence, from single-crystalline erbium-doped yttria nanoparticles with an average diameter of 80,nm, synthesized by a molten salt method, is reported. Outstanding luminescent properties, including sharp and well-resolved photoluminescent lines in the infrared region, outstanding green and red upconversion emissions, and excellent cathodoluminescence, are observed from the nanocrystalline erbium-doped yttria. Moreover, annealing by the high power laser results in a relatively large increase in photoluminescent emission intensity without causing spectral line shift. These desirable properties make these nanocrystals promising for applications in display, bioanalysis and telecommunications. [source] Elementary Many-Particle Processes in Plasma MicrofieldsCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3 2006M. Yu. Abstract The effect of electric and magnetic plasma microfields on elementary many-body processes in plasmas is considered. As detected first by Inglis and Teller in 1939, the electric microfield controls several elementary processes in plasmas as transitions, line shifts and line broadening. We concentrate here on the many-particle processes ionization, recombination, and fusion and study a wide area of plasma parameters. In the first part the state of art of investigations on microfield distributions is reviewed in brief. In the second part, various types of ionization processes are discussed with respect to the influence of electric microfields. It is demonstrated that the processes of tunnel and rescattering ionization by laser fields as well as the process of electron collisional ionization may be strongly influenced by the electric microfields in the plasma. The third part is devoted to processes of microfield action on fusion processes and the effects on three-body recombination are investigated. It is shown that there are regions of plasma densities and temperatures, where the rate of nuclear fusion is accelerated by the electric microfields. This effect may be relevant for nuclear processes in stars. Further, fusion processes in ion clusters are studied. Finally we study in this section three-body recombination effects and show that an electric microfield influences the three-body electron-ion recombination via the highly excited states. In the fourth part, the distribution of the magnetic microfield is investigated for equilibrium, nonequilibrium, and non-uniform magnetized plasmas. We show that the field distribution in a neutral point of a non-relativistic ideal equilibrium plasma is similar to the Holtsmark distribution for the electrical microfield. Relaxation processes in nonequilibrium plasmas may lead to additional microfields. We show that in turbulent plasmas the broadening of radiative electron transitions in atoms and ions, without change of the principle quantum number, may be due to the Zeeman effect and may exceed Doppler and Stark broadening as well. Further it is shown that for optical radiation the effect of depolarization of a linearly polarized laser beams propagating through a magnetized plasma may be rather strong. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Elastic strain and stress determination by Rietveld refinement: generalized treatment for textured polycrystals for all Laue classesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2001N. C. Popa A novel approach to model diffraction line shifts caused by elastic residual or applied stresses in textured polycrystals is proposed. The model yields the complete strain and stress tensors as a function of crystallite orientation, as well as the average values of the macroscopic strain and stress tensors. It is particularly suitable for implementation in Rietveld refinement programs. The requirements on refinable parameters for all crystal Laue classes are given. The effects of sample symmetry are also included and the conditions for strain invariance to both the sample symmetries (texture and stress/strain) are discussed. [source] Time-resolved investigation of the ,1 ro-vibrational Raman band of H2CO with fs-CARSJOURNAL OF RAMAN SPECTROSCOPY, Issue 2 2007A. M. Walser Abstract The technique of femtosecond time-resolved coherent anti-Stokes scattering (fs-CARS) is used to investigate the strongly perturbed ,1 ro-vibrational Raman band of formaldehyde (H2CO). The time-dependent signal is simulated using a ,Watson-'Hamiltonian in A-type reduction and Raman theory for asymmetric rotors. The results are compared with the experimental data. The fs-CARS method measures the evolution of the polarization in a molecular ensemble via superposition of many states and is sensitive to spectral irregularities or line shifts of the involved transitions. ,Coriolis' interactions play a major role in the analysis of the ,1 band of formaldehyde. We successfully simulate the fs-CARS transient signal from the ,1 band of formaldehyde including a model for multiple ,Coriolis' interactions, without the necessity of describing the complete interaction between all the vibrational levels. ,Coriolis' coupling coefficients and energy shifts are derived from the experiment by a least-square fit. The results are discussed and compared to literature values. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||