Raman Scattering
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Plasmonics ◽  
2022 ◽  
RuXin Zhang ◽  
ChaoLing Du ◽  
Lu Sun ◽  
WangXu Rong ◽  
Xiang Li ◽  

2022 ◽  
Vol 12 (1) ◽  
M. B. Shoker ◽  
T. Alhaddad ◽  
O. Pagès ◽  
V. J. B. Torres ◽  
A. V. Postnikov ◽  

AbstractRaman scattering and ab initio Raman/phonon calculations, supported by X-ray diffraction, are combined to study the vibrational properties of Zn1−xBexTe under pressure. The dependence of the Be–Te (distinct) and Zn–Te (compact) Raman doublets that distinguish between Be- and Zn-like environments is examined within the percolation model with special attention to x ~ (0,1). The Be-like environment hardens faster than the Zn-like one under pressure, resulting in the two sub-modes per doublet getting closer and mechanically coupled. When a bond is so dominant that it forms a matrix-like continuum, its two submodes freely couple on crossing at the resonance, with an effective transfer of oscillator strength. Post resonance the two submodes stabilize into an inverted doublet shifted in block under pressure. When a bond achieves lower content and merely self-connects via (finite/infinite) treelike chains, the coupling is undermined by overdamping of the in-chain stretching until a «phonon exceptional point» is reached at the resonance. Only the out-of-chain vibrations «survive» the resonance, the in-chain ones are «killed». This picture is not bond-related, and hence presumably generic to mixed crystals of the closing-type under pressure (dominant over the opening-type), indicating a key role of the mesostructure in the pressure dependence of phonons in mixed crystals.

2022 ◽  
Vol 8 (2) ◽  
Xingzhi Wang ◽  
Jun Cao ◽  
Hua Li ◽  
Zhengguang Lu ◽  
Arielle Cohen ◽  

Electronic Raman scattering activates the investigation of d-d excitations and electron-spin coupling in 2D antiferromagnets.

2022 ◽  
Vol 6 (1) ◽  
Natasha Logan ◽  
Simon A. Haughey ◽  
Lin Liu ◽  
D. Thorburn Burns ◽  
Brian Quinn ◽  

AbstractPesticides are a safety issue globally and cause serious concerns for the environment, wildlife and human health. The handheld detection of four pesticide residues widely used in Basmati rice production using surface-enhanced Raman spectroscopy (SERS) is reported. Different SERS substrates were synthesised and their plasmonic and Raman scattering properties evaluated. Using this approach, detection limits for pesticide residues were achieved within the range of 5 ppb-75 ppb, in solvent. Various extraction techniques were assessed to recover pesticide residues from spiked Basmati rice. Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERs) acetate extraction was applied and characteristic spectral data for each pesticide was obtained from the spiked matrix and analysed using handheld-SERS. This approach allowed detection limits within the matrix conditions to be markedly improved, due to the rapid aggregation of nanogold caused by the extraction medium. Thus, detection limits for three out of four pesticides were detectable below the Maximum Residue Limits (MRLs) of 10 ppb in Basmati rice. Furthermore, the multiplexing performance of handheld-SERS was assessed in solvent and matrix conditions. This study highlights the great potential of handheld-SERS for the rapid on-site detection of pesticide residues in rice and other commodities.

Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 593
Ekaterina Babich ◽  
Sergey Scherbak ◽  
Ekaterina Lubyankina ◽  
Valentina Zhurikhina ◽  
Andrey Lipovskii

The problem of optimizing the topography of metal structures allowing Surface Enhanced Raman Scattering (SERS) sensing is considered. We developed a model, which randomly distributes hemispheroidal particles over a given area of the glass substrate and estimates SERS capabilities of the obtained structures. We applied Power Spectral Density (PSD) analysis to modeled structures and to atomic force microscope images widely used in SERS metal island films and metal dendrites. The comparison of measured and calculated SERS signals from differing characteristics structures with the results of PSD analysis of these structures has shown that this approach allows simple identification and choosing a structure topography, which is capable of providing the maximal enhancement of Raman signal within a given set of structures of the same type placed on the substrate.

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