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Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots.

Alonso-González P, Albella P, Schnell M, Chen J, Huth F, García-Etxarri A, Casanova F, Golmar F, Arzubiaga L, Hueso LE, Aizpurua J, Hillenbrand R - Nat Commun (2012)

Bottom Line: Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally.Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process.We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering.

View Article: PubMed Central - PubMed

Affiliation: CIC nanoGUNE Consolider, 20018 Donostia-San Sebastián, Spain.

ABSTRACT
Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering.

No MeSH data available.


Related in: MedlinePlus

Schematics of a surface-enhanced light scattering process.(a) Inelastic scattering process (ω1≠ω2) from an object (O) in the presence of a metal nanostructure that acts as an optical antenna (A). (b) Elastic scattering process (ω1=ω2=ω). Einc(ω) denotes the incident field, EA(ω) is the field directly radiated by the antenna, and EAOA(ω) is the field radiated by the object via the antenna. To select EAOA, the antenna–object distance d is modulated at frequency Ω, and the detector signal is demodulated at the higher harmonic frequency nΩ.
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f1: Schematics of a surface-enhanced light scattering process.(a) Inelastic scattering process (ω1≠ω2) from an object (O) in the presence of a metal nanostructure that acts as an optical antenna (A). (b) Elastic scattering process (ω1=ω2=ω). Einc(ω) denotes the incident field, EA(ω) is the field directly radiated by the antenna, and EAOA(ω) is the field radiated by the object via the antenna. To select EAOA, the antenna–object distance d is modulated at frequency Ω, and the detector signal is demodulated at the higher harmonic frequency nΩ.

Mentions: In Figure 1a we illustrate the commonly accepted electromagnetic scattering mechanism in SERS32128. An object (O) is located in close proximity to a metal nanostructure. Acting as an antenna (A), the metal nanostructure enhances the incoming field Einc of frequency ω1 by a factor f1, generating a local field Eloc (hot spot) in its proximity:


Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots.

Alonso-González P, Albella P, Schnell M, Chen J, Huth F, García-Etxarri A, Casanova F, Golmar F, Arzubiaga L, Hueso LE, Aizpurua J, Hillenbrand R - Nat Commun (2012)

Schematics of a surface-enhanced light scattering process.(a) Inelastic scattering process (ω1≠ω2) from an object (O) in the presence of a metal nanostructure that acts as an optical antenna (A). (b) Elastic scattering process (ω1=ω2=ω). Einc(ω) denotes the incident field, EA(ω) is the field directly radiated by the antenna, and EAOA(ω) is the field radiated by the object via the antenna. To select EAOA, the antenna–object distance d is modulated at frequency Ω, and the detector signal is demodulated at the higher harmonic frequency nΩ.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3293409&req=5

f1: Schematics of a surface-enhanced light scattering process.(a) Inelastic scattering process (ω1≠ω2) from an object (O) in the presence of a metal nanostructure that acts as an optical antenna (A). (b) Elastic scattering process (ω1=ω2=ω). Einc(ω) denotes the incident field, EA(ω) is the field directly radiated by the antenna, and EAOA(ω) is the field radiated by the object via the antenna. To select EAOA, the antenna–object distance d is modulated at frequency Ω, and the detector signal is demodulated at the higher harmonic frequency nΩ.
Mentions: In Figure 1a we illustrate the commonly accepted electromagnetic scattering mechanism in SERS32128. An object (O) is located in close proximity to a metal nanostructure. Acting as an antenna (A), the metal nanostructure enhances the incoming field Einc of frequency ω1 by a factor f1, generating a local field Eloc (hot spot) in its proximity:

Bottom Line: Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally.Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process.We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering.

View Article: PubMed Central - PubMed

Affiliation: CIC nanoGUNE Consolider, 20018 Donostia-San Sebastián, Spain.

ABSTRACT
Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering.

No MeSH data available.


Related in: MedlinePlus