Correlating Molecular Surface Coverage and Solution-Phase Nanoparticle Concentration to Surface-Enhanced Raman Scattering Intensities

2011 ◽  
Vol 115 (38) ◽  
pp. 18511-18517 ◽  
Author(s):  
Marie Carmelle S. Pierre ◽  
Prescott M. Mackie ◽  
Maryuri Roca ◽  
Amanda J. Haes
Keyword(s):  
Raman Scattering ◽  
Surface Coverage ◽  
Surface Enhanced Raman Scattering ◽  
Solution Phase ◽  
Molecular Surface ◽  
Nanoparticle Concentration ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Surface-Enhanced Raman Scattering Spectroscopy of Resveratrol

2008 ◽  
Vol 61 (12) ◽  
pp. 921 ◽  
Author(s):  
Jitraporn Vongsvivut ◽  
Evan G. Robertson ◽  
Don McNaughton
Keyword(s):  
Raman Scattering ◽  
Density Functional ◽  
Surface Coverage ◽  
Density Functional Theory Calculations ◽  
Surface Enhanced Raman Scattering ◽  
Lower Surface ◽  
High Concentration ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

We report here, for the first time, the surface-enhanced Raman scattering (SERS) spectra of resveratrol using KNO3-aggregated citrate-reduced silver (Ag) colloids. The technique provided a substantial spectral enhancement and therefore good quality spectra of resveratrol at parts per million (ppm) concentrations. The detection limit was found to be <1 μM, equivalent to <0.2 ppm. The SERS profile additionally closely resembled its normal solid-state Raman spectrum with some changes in relative intensity. These intensity changes, together with a precise band assignment aided by density functional theory calculations at the B3LYP/6–31G(d) level, allowed the determination of the structural orientation of the adsorbed resveratrol on the surface of the metal nanoparticles. In particular, the SERS spectra obtained at different resveratrol concentrations exhibited concentration-dependent features, suggesting an influence of surface coverage on the orientation of the adsorbed molecules. At a high concentration, an adoption of close-to-upright orientation of resveratrol adsorbed on the metal surface through the p-OH phenyl ring is favoured. The binding structure is, however, altered at lower surface coverage when the concentration decreases to a tilted orientation with the trans-olefin C=C bond aligning closer to parallel to the surface of the Ag nanoparticles.

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