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Scattering Cross Section (scattering + cross_section)
Selected AbstractsThe role of resonances in building cross sections: The Mittag-Leffler expansion in a two-channel scatteringINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2009Ksenia Shilyaeva Abstract The Mittag-Leffler formalism for identifying resonance contributions to a two-body scattering cross section is extended here from the one channel case to the two channel case. The reduced partial wave cross sections based on subtracting S-matrix residues are compared with expressions which can be derived from the Breit-Wigner approximation. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] FT-Raman, FTIR and density functional theory studies of a hydrogen-bonded formamide:pyridine complexJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2009Filipe S. F. Jacinto Abstract Raman and IR experiments have been carried out on formamide (FA) and pyridine (Py) mixtures at different compositions. The appearance of a new Raman band at 996 cm,1 (,1 region of Py), whose intensity depends on the FA concentration, is assigned to an FA:Py adduct and this result is in excellent agreement with those of other authors who employed noisy light-based coherent Raman scattering spectroscopy (I(2) CARS). Another band at 1587 cm,1 (,8 region of Py) has been observed for the first time by using Raman and IR spectroscopies. Its intensity shows the same dependence on the FA concentration and this fact allows us to also attribute it to an FA:Py adduct. The good relationship between the Raman and IR data demonstrates the potential of the vibrational spectroscopy for this kind of study. Owing to higher absolute Raman scattering cross section, the ,1 region of Py has been chosen for the quantitative analysis and a stoichiometry of 1:1 FA:Py is reported. The experimental data are very well supported by the density functional theory (DFT) calculation, which was employed for the first time to the present system. Furthermore, the actual investigation shows an excellent agreement with those reported from computational calculations for similar systems. A comparison with our previous studies confirms that the solvent dielectric constant determines the stoichiometry of a given Lewis acid,base adduct in the infinite dilution limit. Copyright © 2009 John Wiley & Sons, Ltd. [source] Nanostructured gold surfaces as reproducible substrates for surface-enhanced Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 3 2007M. Sackmann Abstract Raman spectroscopy is a common tool for the qualitative and quantitative chemical analysis of molecules. Although the unique identification of molecules is possible via their vibrational lines, high concentrations (mmol/l) are needed for their nonresonant excitation owing to their low scattering cross section. The intensity of the Raman spectra is amplified by the use of the surface-enhanced Raman scattering (SERS) technique. While the use of silver sols results only in a limited reproducibility of the Raman line intensities, lithographically designed, nanostructured gold surfaces used as SERS-active substrates should, in principle, combine the high sensitivity with better reproducibility. For this purpose, we have produced gratings of gold dots on Si(001) surfaces by means of electron beam lithography. Qualitative and quantitative investigations of crystal violet (CV) performed using nanostructured surfaces give high reproducibility and enhancement of the Raman lines. The substrates are reusable after cleaning; all results presented could be obtained from a single SERS substrate. For the experiments very low laser powers were used. Copyright © 2006 John Wiley & Sons, Ltd. [source] Light scattering from anisotropic particles: propagation, localization, and nonlinearityLASER & PHOTONICS REVIEWS, Issue 2 2010C.W. Qiu Abstract Plasmon resonances and extraordinary light scatterings of a nanoparticle with radial anisotropy are studied and summarized. The coupling between localized surface plasmons and far-field quantities is discussed. It is found that the presence of radial anisotropy redistributes the localization of plasmons and also results in certain novel phenomena in the far zone, which provide the possibility of scattering control such as electromagnetic transparency, enhanced scattering cross section, etc. The nonlinear optical response is explored in order to yield deeper physical insight into the interaction between plasmons and incident light. [source] Ultra-small-angle X-ray scattering at the Advanced Photon SourceJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2009Jan Ilavsky The design and operation of a versatile ultra-small-angle X-ray scattering (USAXS) instrument at the Advanced Photon Source (APS) at Argonne National Laboratory are presented. The instrument is optimized for the high brilliance and low emittance of an APS undulator source. It has angular and energy resolutions of the order of 10,4, accurate and repeatable X-ray energy tunability over its operational energy range from 8 to 18,keV, and a dynamic intensity range of 108 to 109, depending on the configuration. It further offers quantitative primary calibration of X-ray scattering cross sections, a scattering vector range from 0.0001 to 1,Å,1, and stability and reliability over extended running periods. Its operational configurations include one-dimensional collimated (slit-smeared) USAXS, two-dimensional collimated USAXS and USAXS imaging. A robust data reduction and data analysis package, which was developed in parallel with the instrument, is available and supported at the APS. [source] | ||||||||||