Complementary Surface‐Enhanced Raman Scattering (SERS) and IR Absorption Spectroscopy (SEIRAS) with Nanorods‐on‐a‐Mirror

Abstract

The surface-enhanced counterparts of Raman scattering (SERS) and infrared (IR) absorption (SEIRAS) are commonly used to probe and identify nanoscale matter and small populations of molecules. The contrasting selection rules offer complementary vibrational information of bulk solids or solutions. In this study, a complementary surface-enhanced vibrational spectroscopy approach is presented to probe the vibrational signature of metal-bound molecular monolayers. Nanocavities are designed and produced with sharp and tunable visible (VIS) and mid-IR gap resonances by placing nanorods on a mirror that is coated with a thin dielectric spacer. Their VIS resonances are tuned to match a 1.61 eV (770 nm) resonant excitation for SERS, while their mid-IR resonances span the 1500-2800 cm −1 range (6.5-3.5 µm) in high resolution for SEIRAS, targeting CN bond vibrations at 2220 cm −1 . Both the VIS and mid-IR gap modes support spatially overlapping and highly enhanced near-fields ensuring strong SERS and SEIRAS signals from the same monolayer molecular population. The differences in the vibrational information obtained with the two surface-enhanced spectroscopies when probing coupled molecular vibrations are highlighted and the advantages of using such a platform for investigating cavity-modified chemical reactions are discussed.

Interconnected CoNi-Se Hollow Flakes through Reduced Graphene Oxide Sheets as a Cathode Material for Hybrid Supercapacitors

“…Observably, XRD peak corresponding to (012) vanishes in CoNi-Se/rGO, potentially indicative of a preferred growth direction of the material on the rGO surface . Notably, the disappearance of Raman CN stretching at 2213 cm –1 (Figure c) and CN FTIR stretching at 2260 cm –1 (Figure d), features associated with the cyano-bridged coordination polymer, following calcination, serves as conclusive evidence affirming the conversion of CoNi-CP/GO into CoNi-Se/rGO . The I D / I G ratios for CoNi-CP/GO and CoNi-Se/rGO are measured at 0.92 and 1.05, respectively.…”

“…34 Notably, the disappearance of Raman CN stretching at 2213 cm −1 (Figure 1c) and CN FTIR stretching at 2260 cm −1 (Figure 1d), features associated with the cyano-bridged coordination polymer, following calcination, serves as conclusive evidence affirming the conversion of CoNi-CP/GO into CoNi-Se/rGO. 35 The I D /I G ratios for CoNi-CP/GO and CoNi-Se/rGO are measured at 0.92 and 1.05, respectively. The intensified I D /I G ratio observed in CoNi-Se/rGO denotes a heightened disorder within the graphene matrix, providing compelling evidence for the transformation of GO into rGO.…”

High Accuracy of Clinical Verification of Electrohydrodynamic-Driven Nanobox-on-Mirror Platform for Molecular Identification of Respiratory Viruses

“…We also aim to promote the usage of the E-NoM platform in clinical sample detection in a bid to translate emerging nanotechnology into real-world utility. Leveraging on the electromagnetic coupling of the localized and propagating surface plasmons, the E-NoM platform displays extremely strong “hot spots” in the nanocavity (<50 nm) between the nanostructure and the mirror that can significantly amplify Raman signals for applications in SERS. − The extremely narrow Raman spectral lines (∼1–2 cm –1 ) that reduce potential spectral overlap demonstrate the overwhelming advantage in the parallel detection of multitargets . To enable effective electromagnetic coupling, we synthesized anisotropic core–shell nanostructures with the use of gold–silver alloy nanoboxes (NBs) as the core plasmonic material, which possesses a stronger electromagnetic field than the commonly used spherical nanostructures. , Notably, the further design of NB-based core–shell nanostructures features a reproducible and stable signal readout as well as a further amplification of electromagnetic field given the additional coupling between the core and the shell. , Furthermore, we fabricated the gold microelectrode as the mirror with the capability of maneuvering the electrohydrodynamic fluidic force within the nanometer scale under the application of alternating current.…”

Flexible nanohybrid substrates utilizing gold nanocubes/nano mica platelets with 3D lightning-rod effect for highly efficient bacterial biosensors based on surface-enhanced Raman scattering

“…12 Owing to their flat surfaces, these particles can self-assemble into large-scale orderly nanostructures that are stacked in a specific order; thus, they can potentially be used for surface-enhanced Raman scattering (SERS). [13][14][15] AuNCs are typically prepared using seed growth; 16 the synthesis process has limitations such as a long preparation time and cumbersome steps. Therefore, this study uses a seed-mediated method to prepare AuNCs, 17 making the AuNC-preparation process simpler and faster.…”