Molecular hot spots in surface-enhanced Raman scattering
Abstract
The chemical and electromagnetic (EM) enhancements both contribute to surface-enhanced Raman scattering (SERS). It is well-known that the EM enhancement is induced by the intense local field of surface plasmon resonance (SPR). This report shows that the polarizability of the molecules adsorbed on the metal surface can lead to another channel for the EM field enhancement. When aromatic molecules are covalently bonded to the Au surface, they strongly interact with the plasmon, leading to a modification of the absorption spectrum and a strong SERS signal. The effect is seen in both 3 nm-Au nanoparticles with a weak SPR and 15 nm-Au nanoparticles with a strong SPR, suggesting that the coupling is through both EM field and chemical means. Linear-chain molecules on the 3 nm-Au nanoparticles do not have a SERS signal. However, when the aromatic and linear molecules are co-adsorbed, the strong SPR/molecular polarizability interaction spatially extends the local EM field, leading to a strong SERS signal from the linear-chain molecules. The results show that aromatic molecules immobilized on Au can create "hot spots" just like plasmonic nanostructures.
Additional Information
© The Royal Society of Chemistry 2020. Received 12th September 2020, Accepted 23rd October 2020. N. W. is partially supported by the Armstrong-Siadat Professorship Endowment. Conflicts of interest. There are no conflicts to declare.Attached Files
Supplemental Material - d0nr06579j1.pdf
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Additional details
- Eprint ID
- 106467
- Resolver ID
- CaltechAUTHORS:20201105-160425769
- Armstrong-Siadat Professorship Endowment
- Created
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2020-11-06Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field