Enhanced Raman Scattering with Dielectrics

Alessandri, Ivano; Lombardi, John R.

doi:10.1021/acs.chemrev.6b00365

Cited by 542 publications

(464 citation statements)

References 409 publications

(729 reference statements)

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“…[4,11] However, their developments are often limited by their increasingly exposed shortcomings, such as the low number of varieties, poor biocompatibility, easy agglomeration, secondary pollution, and nonreusability. [13,14] Additionally, the high selectivity of semiconductor SERS substrates to probed molecules can also become a unique advantage when distinguishing a specific molecule from the complex environment with many other molecules. Although their enhancement effect is usually low, between 10-10 5 , and the problem of their unclear and controversial enhancement mechanism has persisted, semiconductors can still become one of the most promising candidate SERS substrate materials due to their rich variety, excellent biocompatibility, and useful versatility.…”

Section: Introductionmentioning

confidence: 99%

A Novel Ultra‐Sensitive Semiconductor SERS Substrate Boosted by the Coupled Resonance Effect

et al. 2019

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Recent achievements in semiconductor surface‐enhanced Raman scattering (SERS) substrates have greatly expanded the application of SERS technique in various fields. However, exploring novel ultra‐sensitive semiconductor SERS materials is a high‐priority task. Here, a new semiconductor SERS‐active substrate, Ta 2 O 5 , is developed and an important strategy, the “coupled resonance” effect, is presented, to optimize the SERS performance of semiconductor materials by energy band engineering. The optimized Mo‐doped Ta 2 O 5 substrate exhibits a remarkable SERS sensitivity with an enhancement factor of 2.2 × 10 7 and a very low detection limit of 9 × 10 −9 m for methyl violet (MV) molecules, demonstrating one of the highest sensitivities among those reported for semiconductor SERS substrates. This remarkable enhancement can be attributed to the synergistic resonance enhancement of three components under 532 nm laser excitation: i) MV molecular resonance, ii) photoinduced charge transfer resonance between MV molecules and Ta 2 O 5 nanorods, and iii) electromagnetic enhancement around the “gap” and “tip” of anisotropic Ta 2 O 5 nanorods. Furthermore, it is discovered that the concomitant photoinduced degradation of the probed molecules in the time‐scale of SERS detection is a non‐negligible factor that limits the SERS performance of semiconductors with photocatalytic activity.

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Section: Introductionmentioning

confidence: 99%

A Novel Ultra‐Sensitive Semiconductor SERS Substrate Boosted by the Coupled Resonance Effect

et al. 2019

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“…Some studies showed that TiO 2 represents one of the most promising materials for Surface Enhanced Raman Scattering (SERS), because of its high refractive index, versatile surface functionalization, synergistic coupling to plasmonic nanoparticles, cocatalysts, and so on. Thus it could be used to analyze and monitor the process of photocatalytic degradation [7,8,9]. Meanwhile, TiO 2 with its extraordinary chemical stability, environmentally friendly, and biocompatible characteristics, has been intensively investigated as a benchmark material for many photocatalytic reactions [10,11,12,13,14].…”

Section: Introductionmentioning

confidence: 99%

The Synthesis of a Core-Shell Photocatalyst Material YF3:Ho3+@TiO2 and Investigation of Its Photocatalytic Properties

Zhou

Long

et al. 2017

Materials

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In this paper, YF3:Ho3+@TiO2 core-shell nanomaterials were prepared by hydrolysis of tetra-n-butyl titanate (TBOT) using polyvinylpyrrolidone K-30 (PVP) as the coupling agent. Characterization methods including X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) under TEM, X-ray photoelectron spectroscopy (XPS), fluorescence spectrometry, ultraviolet-visible diffuse reflectance spectroscopy, and electron spin resonance (ESR) were used to characterize the properties and working mechanism of the prepared photocatalyst material. They indicated that the core phase YF3 nanoparticles were successfully coated with a TiO2 shell and the length of the composite was roughly 100 nm. The Ho3+ single-doped YF3:Ho3+@TiO2 displayed strong visible absorption peaks with wavelengths of 450, 537, and 644 nm, respectively. By selecting these three peaks as excitation wavelengths, we could observe 288 nm (5D4→5I8) ultraviolet emission, which confirmed that there was indeed an energy transfer from YF3:Ho3+ to anatase TiO2. In addition, this paper investigated the influences of different TBOT dosages on photocatalysis performance of the as-prepared photocatalyst material. Results showed that the YF3:Ho3+@TiO2 core-shell nanomaterial was an advanced visible-light-driven catalyst, which decomposed approximately 67% of rhodamine b (RhB) and 34.6% of phenol after 10 h of photocatalysis reaction. Compared with the blank experiment, the photocatalysis efficiency was significantly improved. Finally, the visible-light-responsive photocatalytic mechanism of YF3:Ho3+@TiO2 core-shell materials and the influencing factors of photocatalytic degradation were investigated to study the apparent kinetics, which provides a theoretical basis for improving the structural design and functions of this new type of catalytic material.

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“…1 This emerging interest stems from several factors. One is the possibility to exploit a rich variety of opportunities to tune the Raman response.…”

Section: Resonant Laser Printingmentioning

confidence: 99%

Non-Plasmonic SERS with Silicon: Is It Really Safe? New Insights into Opto-Thermics of Core/Shell Microbeads

Bontempi¹,

Vassalini²,

Danesi³

et al. 2018

Preprint

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Resonant Laser PrintingAll-dielectric and semiconductor-based optical antennas are intensively investigated as promising substrates for surface enhanced Raman scattering (SERS). 1 This emerging interest stems from several factors. One is the possibility to exploit a rich variety of opportunities to tune the Raman response. For example, the chemical enhancement can be widely modulated by controlling charge transfer and adsorption-induced changes of the molecular polarizability of a given analyte.In parallel, the electromagnetic enhancement can take advantage of Mie-type resonances, light trapping and related optical effects to increase sensitivity and selectivity of the Raman response.Further major benefits of non-plasmonic SERS are low-invasiveness (plasmonic heating and plasmon-driven catalysis are avoided) 2-6 and high reproducibility, which make dielectrics more advantageous than metals for many types of Raman analysis, including the real-time monitoring of chemical reactions. These hallmarks are ultimately related to the lossless nature of dielectrics, which avoids the generation of strong local heating under light irradiation. Among the different types of dielectrics and semiconductors that have been proposed so far, SiO 2 /TiO 2 core/shell beads (T-rex) 7 demonstrated unique performances in sensing environmental pollutants and biomarkers. 6-10In particular, micron-sized beads can be individually visualized by optical microscopy and exploited as Mie resonators able to act as all-in-one colloidal platforms combining SERS, mass spectrometry and optical sensing. 11 As the SERS efficiency of these resonators is closely related to the refractive index contrast between core and shell, the replacement of the TiO 2 with a higher index material could further improve the performance of these systems. 12 In this regard, Si represents a natural choice in terms of high refractive index (n∼4 at the most common Raman exciting wavelengths) and compatibility with sensing devices. [13][14][15] Maier and co-workers demonstrated that dimers of spheres and nanodisks, either made of GaP or Si, are able to produce a good near-field enhancement, yet with minimal heating losses if compared with the analogous gold counterparts. (100) substrates by rf-magnetron sputtering and selected for the study (details in Supporting Information, SI 1 and SI 2). The laser spot size of the three wavelengths is commensurate with the 2 µm-sized beads, which enables a geometrically efficient light in-coupling. On the other hand, the laser spot size is about 1/3 of that of the whole sphere in the case of∼ 6.5 µm-sized cores. Both single beads and three-dimensional (3D) colloidal crystals were analysed. ) Raman spectra of the samples before (blue) and after (red) 500s of exposure to an exciting laser beam (laser wavelength: 633 nm, power: 5mW); c) 6_Si100 and d) 2_Si100 samples: e) Raman intensity ratio (IαSi/IcSi) as function of time respectively for 6_Si100 (pink) and for 2_Si100 (light blue); f) Threshold laser power as function of shell thickness...

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Enhanced Raman Scattering with Dielectrics

Cited by 542 publications

References 409 publications

A Novel Ultra‐Sensitive Semiconductor SERS Substrate Boosted by the Coupled Resonance Effect

A Novel Ultra‐Sensitive Semiconductor SERS Substrate Boosted by the Coupled Resonance Effect

The Synthesis of a Core-Shell Photocatalyst Material YF3:Ho3+@TiO2 and Investigation of Its Photocatalytic Properties

Non-Plasmonic SERS with Silicon: Is It Really Safe? New Insights into Opto-Thermics of Core/Shell Microbeads

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