scholarly journals Purcell factor and local intensity enhancement in surface-enhanced Raman scattering

Nanophotonics ◽  
2019 ◽  
Vol 8 (3) ◽  
pp. 429-434 ◽  
Author(s):  
Stanislav I. Maslovski ◽  
Constantin R. Simovski
Keyword(s):  
Raman Scattering ◽  
Surface Enhanced Raman Scattering ◽  
Raman Gain ◽  
Purcell Factor ◽  
Intensity Enhancement ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering ◽  
Local Intensity ◽  
Further Development

AbstractWe prove that, at any point of any reciprocal structure, the local field intensity enhancement, which is averaged over the incident wave polarizations and the incidence directions, exactly coincides with the radiative part of the Purcell factor, which is averaged over the orientations of the emitter. This result is important for gaining a better understanding of the electromagnetic Raman gain in the surface-enhanced Raman scattering and for the further development of this technique.

scholarly journals Surface Enhanced Raman Scattering on Regular Arrays of Gold Nanostructures: Impact of Long-Range Interactions and the Surrounding Medium

Nanomaterials ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 2201 ◽  
Author(s):  
Iman Ragheb ◽  
Macilia Braïk ◽  
Stéphanie Lau-Truong ◽  
Abderrahmane Belkhir ◽  
Anna Rumyantseva ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Long Range ◽  
Electromagnetic Coupling ◽  
Surrounding Medium ◽  
Surface Enhanced Raman Scattering ◽  
Localized Surface Plasmon ◽  
Raman Gain ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Long-range interaction in regular metallic nanostructure arrays can provide the possibility to manipulate their optical properties, governed by the excitation of localized surface plasmon (LSP) resonances. When assembling the nanoparticles in an array, interactions between nanoparticles can result in a strong electromagnetic coupling for specific grating constants. Such a grating effect leads to narrow LSP peaks due to the emergence of new radiative orders in the plane of the substrate, and thus, an important improvement of the intensity of the local electric field. In this work, we report on the optical study of LSP modes supported by square arrays of gold nanodiscs deposited on an indium tin oxyde (ITO) coated glass substrate, and its impact on the surface enhanced Raman scattering (SERS) of a molecular adsorbate, the mercapto benzoic acid (4-MBA). We estimated the Raman gain of these molecules, by varying the grating constant and the refractive index of the surrounding medium of the superstrate, from an asymmetric medium (air) to a symmetric one (oil). We show that the Raman gain can be improved with one order of magnitude in a symmetric medium compared to SERS experiments in air, by considering the appropriate grating constant. Our experimental results are supported by FDTD calculations, and confirm the importance of the grating effect in the design of SERS substrates.

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