Chemical adsorption of salicylate on silver - A systematic approach to the interpretation of surface-enhanced vibrational spectra

2004 ◽  
Vol 82 (6) ◽  
pp. 987-997 ◽  
Author(s):  
P J.G Goulet ◽  
R F Aroca
Keyword(s):  
Salicylic Acid ◽  
Raman Spectra ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Ir And Raman Spectra ◽  
Chemical Adsorption ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Ir And Raman

In this work, surface-enhanced vibrational spectroscopy and normal vibrational spectroscopy as well as density functional theory (DFT) computational methods have been employed to investigate the nature of the chemical adsorption and orientation of the surface species generated from salicylic acid at silver surfaces. The structure of salicylic acid and its IR and Raman spectra are determined at the B3LYP/6-311+G(d,p) level of theory. These results are used in the assignment of the vibrational spectra. Surface-enhanced Raman scattering (SERS) spectra obtained from silver island films thinly coated with salicylic acid confirm chemical adsorption on the Ag nanostructures. To probe the nature of this surface complex, the optimized geometries and IR and Raman spectra of two model salicylate-silver complexes (Ag1 and Ag2) were calculated at the B3LYP/Lanl2DZ level of theory. It was found that good agreement exists between experimentally observed SERS spectra and the simulated SERS spectra of a complex with the salicylate monoanion bound to a Ag+ ion through its carboxylate group (Ag1). The carboxylate silver salt of salicylic acid (essentially the Ag1 complex) was also prepared, and its IR and Raman spectra were recorded for comparison with the surface-enhanced vibrational spectra. These results, along with the application of surface selection rules, suggest that salicylic acid is deprotonated at silver surfaces, interacting through its carboxylate group alone, and is preferentially in a tilted head-on orientation.Key words: chemisorption, salicylic acid, silver, density functional theory, surface-enhanced Raman scattering, reflection-absorption IR spectroscopy, surface-enhanced IR absorption.

Vibrational and Surface-Enhanced Raman Spectra of 1,6-Diphenyl-1,3,5-hexatriene

2007 ◽  
Vol 61 (9) ◽  
pp. 1001-1006 ◽  
Author(s):  
Igor O. Osorio-Roman ◽  
Victor C. Vargas ◽  
Ricardo F. Aroca
Keyword(s):  
Raman Spectra ◽  
Vibrational Spectra ◽  
Density Functional ◽  
Geometry Optimization ◽  
Functional Theory ◽  
Cis And Trans Isomers ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Cis And Trans

The vibrational spectra and surface-enhanced Raman scattering (SERS) of 1,6-diphenyl-1,3,5-hexatriene (DPH) are discussed. The fundamental vibrational frequencies, overtones, and combinations observed in the infrared and Raman spectra of DPH are reported. The interpretation of the observed vibrational spectra was supported by a complete geometry optimization, followed by vibrational frequency and intensity computations for the cis- and trans- isomers of the DPH using density functional theory at the B3LYP/6-31G(d,p) level of theory. Because the molecule is photo-chemically active on Ag metal surfaces, the best SERS results for silver islands were obtained at low temperature and low energy density of the exciting laser line. DPH SERS on Au films was obtained at room temperature.

scholarly journals C2: An Asymmetric Specie ?

2020 ◽  
Author(s):  
Robson de Farias
Keyword(s):  
Chemical Bond ◽  
Raman Spectra ◽  
Density Functional ◽  
Functional Approach ◽  
Ir And Raman Spectra ◽  
Basis Set ◽  
Ir And Raman

<p> The present work is another contribution to a better understanding of the chemical bond in C<sub>2</sub>. Several density functional approach/basis set provided calculated IR and Raman spectra with simultaneous active bands. Hence, the hypothesis of electronic asymmetry in C<sub>2</sub> [1] was reinforced. </p>

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