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Density functional theory study on surface-enhanced Raman scattering of 4,4'-azopyridine on silver.

Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy (2009-02-03)
Zhiping Zhuang, Xiaohong Shang, Xu Wang, Weidong Ruan, Bing Zhao
RESUMEN

Surface-enhanced Raman scattering (SERS) of 4,4'-azopyridine (AZPY) on silver foil substrate was measured under 1064nm excitation lines. Density-functional theory (DFT) methods were used to calculate the structure and vibrational spectra of models such as Ag-AZPY, Ag(4)-AZPY and Ag(6)-AZPY complexes with B3LYP/6-31++G(d,p)(C,H,N)/Lanl2dz(Ag) basis set. The Raman bands of AZPY were identified on the ground of analog computation of potential energy distribution. The calculated spectra of Ag(4)-AZPY and Ag(6)-AZPY models were much approximated to the experimental results than that of Ag-AZPY model. The DFT results showed that the angles between two pyridyl rings keep 0 degrees from AZPY to Ag-AZPY, Ag(4)-AZPY and Ag(6)-AZPY model. The energy gaps between the HOMO and LUMO changed from 363 to 1140nm for AZPY-Ag complexes according to the DFT results. An conclusion was conceived that chemical enhancement mechanism may play an important role in the SERS of AZPY on silver substrate.

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Silver, foil, 150x150mm, thickness 0.25mm, as rolled, 99.95+%
Silver, foil, 100x100mm, thickness 0.125mm, as rolled, 99.95+%
Silver, foil, 150x150mm, thickness 0.5mm, as rolled, 99.99+%
Silver, foil, 25x25mm, thickness 0.5mm, as rolled, 99.99+%
Silver, foil, 100x100mm, thickness 0.5mm, as rolled, 99.99+%
Silver, foil, 50x50mm, thickness 0.125mm, as rolled, 99.99+%
Silver, foil, 100x100mm, thickness 0.5mm, as rolled, 99.95+%
Silver, foil, 100x100mm, thickness 0.20mm, as rolled, 99.95+%
Silver, foil, 50x50mm, thickness 0.5mm, as rolled, 99.99+%
Silver, foil, 50x50mm, thickness 0.125mm, as rolled, 99.95+%
Silver, foil, 1m coil, thickness 0.025mm, as rolled, 99.95+%
Silver, foil, 100x100mm, thickness 0.1mm, as rolled, 99.95+%
Silver, foil, 150x150mm, thickness 0.5mm, as rolled, 99.95+%
Silver, foil, 25x25mm, thickness 1.0mm, as rolled, 99.99+%
Silver, foil, 300x300mm, thickness 0.1mm, annealed, 99.95+%
Silver, foil, 50x50mm, thickness 0.25mm, as rolled, 99.95+%
Silver, foil, 25x25mm, thickness 0.125mm, as rolled, 99.99+%
Silver, foil, 50x50mm, thickness 0.1mm, as rolled, 99.95+%
Silver, foil, light tested, 25x25mm, thickness 0.05mm, as rolled, 99.95+%
Silver, foil, 50x50mm, thickness 0.20mm, as rolled, 99.95+%
Silver, foil, 25mm disks, thickness 0.1mm, as rolled, 99.95+%
Silver, foil, not light tested, 50x50mm, thickness 0.01mm, 99.95+%
Silver, foil, 25x25mm, thickness 0.25mm, as rolled, 99.95+%
Silver, foil, 50x50mm, thickness 1.0mm, as rolled, 99.99+%
Silver, foil, 4mm disks, thickness 0.004mm, 99.97%
Silver, foil, 6mm disks, thickness 0.007mm, 99.97%
Silver, foil, not light tested, 25x25mm, thickness 0.009mm, 99.97%
Silver, foil, 100x100mm, thickness 0.15mm, as rolled, 99.95+%
Silver, foil, 100x100mm, thickness 0.1mm, annealed, 99.95+%
Silver, foil, 100x100mm, thickness 0.25mm, as rolled, 99.95+%