Abstract
Surface-enhanced Raman scattering (SERS) has demonstrated single-molecule sensitivity and is becoming intensively investigated due to its significant potential in chemical and biomedical applications. SERS sensing is highly dependent on the substrate, where excitation of the localized surface plasmons (LSPs) enhances the Raman scattering signals of proximate analyte molecules. This paper reviews research progress of SERS substrates based on both plasmonic materials and nano-photonic structures. We first discuss basic plasmonic materials, such as metallic nanoparticles and nano-rods prepared by conventional bottom-up chemical synthesis processes. Then, we review rationally-designed plasmonic nano-structures created by top-down approaches or fine-controlled synthesis with high-density hot-spots to provide large SERS enhancement factors (EFs). Finally, we discuss the research progress of hybrid SERS substrates through the integration of plasmonic nano-structures with other nano-photonic devices, such as photonic crystals, bio-enabled nanomaterials, guided-wave systems, micro-fluidics and graphene.
Highlights
The first observation of enhanced Raman spectra of pyridine on rough silver film was reported in1974 [1], but the increment of Raman signals was incorrectly attributed to a larger number of molecules on the corrugated surface of the electrode
They reported significantly suppressed photoluminescence background by attributing the quenched PL signals to the strong resonance energy transfer from Au to single-layer graphene (SLG). They suggested that the combination of Au films and SLG can be used in the characterization of low concentration molecules with relatively weak Raman signals
surface-enhanced Raman scattering (SERS) is a highly-sensitive technique that allows for the detection of molecules in very low concentrations and provides rich structural information
Summary
The first observation of enhanced Raman spectra of pyridine on rough silver film was reported in. In addition to optimizing the conventional SERS substrates using bottom-up chemical synthesis processes and top-down nanofabrication techniques, there has been a new research trend in hybrid SERS substrates by integrating plasmonic nanostructures with other nano-photonic platforms, such as gratings [41], photonic crystals [42], hollow-core waveguides [43], resonant cavities [44] and micro-fluidics [45]. Such hybrid SERS substrates can provide unprecedented sensitivity, high reproducibility and add new functionality into existing SERS substrates
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