Surface enhanced Raman scattering of p-aminothiophenol self-assembled monolayers in sandwich structure fabricated on glass

Abstract

A sandwich structure consisting of Ag nanoparticles (NPs), p-aminothiophenol (p-ATP) self-assembled monolayers (SAMs), and Ag NPs was fabricated on glass and characterized by surface enhanced Raman scattering (SERS). The SERS spectrum of a p-ATP SAM in such sandwich structure shows that the electromagnetic enhancement is greater than that on Ag NPs assembled on glass. The obtained enhancement factors (EF) on solely one sandwich structure were as large as 6.0±0.62×104 and 1.2±0.62×107 for the 7a and 3b(b2) vibration modes, respectively. The large enhancement effect of p-ATP SAMs is likely a result of plasmon coupling between the two layers of Ag NP (localized surface plasmon) resonance, creating a large localized electromagnetic field at their interface, where p-ATP resides. Moreover, the fact that large EF values (∼1.9±0.7×104 and 9.4±0.7×106 for the 7a- and b2-type vibration modes, respectively) were also obtained on a single sandwich structure of Au NPs∕p-ATPSAMs∕Ag NPs in the visible demonstrates that the electromagnetic coupling does not exist only between Ag NPs but also between Au and Ag NPs. The lower EF values on Au-to-Ag NPs compared to those on Ag-to-Ag NPs demonstrate that the Au-to-Ag coupling must be less effective than the Ag-to-Ag coupling for the induction of SERS in the visible.

Long‐Term Stable Silver Subsurface Ion‐Exchanged Glasses for SERS Applications

“…[8,19] We would like to point out that an enhancement of 10 7 cannot be achieved from isolated particles [20] but is due to the contribution of a favourable agglomeration of particles located very close together. This is also confirmed by the morphological information provided by electron microscopy (see Figure 1).…”

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Facile fabrication of large area of aggregated gold nanorods film for efficient surface-enhanced Raman scattering

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