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Density functional theory study on surface-enhanced Raman scattering of 4,4'-azopyridine on silver.
- Source :
-
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy [Spectrochim Acta A Mol Biomol Spectrosc] 2009 Jun; Vol. 72 (5), pp. 954-8. Date of Electronic Publication: 2008 Dec 25. - Publication Year :
- 2009
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Abstract
- 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.
- Subjects :
- Molecular Structure
Spectrum Analysis, Raman
Pyridines chemistry
Silver chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1386-1425
- Volume :
- 72
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy
- Publication Type :
- Academic Journal
- Accession number :
- 19185534
- Full Text :
- https://doi.org/10.1016/j.saa.2008.12.027