Metal-enhanced fluorescence

Geddes, Chris D.

doi:10.1039/c3cp90129g

Cited by 207 publications

(202 citation statements)

References 3 publications

(3 reference statements)

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“…Arranged in either isolated or near-field coupled architectures, optical nanoantennas [1,2] are nowadays used for a broad set of plasmon enhanced spectroscopies (PlEnS) such as Surface Enhanced Raman Scattering (SERS), [3][4][5] Metal Enhanced Fluorescence (MEF), [6][7][8] and Surface-Enhanced Infrared Absorption-Scattering (SEIRA-SEIRS) [9,10]. PlEnS enable the development of high sensitivity, multiband spectroscopic nanosensors for label-free detection of chemical and biomolecular compounds [11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

On the SERS depolarization ratio

et al. 2015

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According to the E 4 model, [18][19][20][21][22][23][24] in SERS the nanoantenna plays a twofold role: firstly it amplifies the local field (excitation-field enhancement) confining it to nanoscale regions (hot spots), and secondly it magnifies the Raman scattering (re-radiation enhancement). Molecules lying in the hot spots (located at the edges of individual nanoantennas or in the nanocavities between near-field coupled NPs [15,[25][26][27][28][29]) experience an amplified local field and an enhanced re-radiation whenever both the wavelengths of the laser pump (λ L ) and of the induced Raman dipole (λ R ) are close to the LSPR wavelength (λ LSPR ) [24]. It is well known that the enhanced local field is polarization sensitive. The only component of the incident field yielding the local field amplification is the one capable of exciting the LSPR of the antenna [30][31][32][33]. On the other hand, in near-field coupled nanoantennas the re-radiation effect yields a selective enhancement of the Raman dipole component parallel to the nanocavity axis at the single molecule level, linearizing the polarization of the Raman field [34][35][36][37][38].The re-radiation effect, therefore, causes a strong modification of the polarization of the SERS field, whose components will be altered with respect to what would have been measured in normal Raman spectroscopy in absence of the nanoantennas. In addition, such an alteration is dependent on the orientation of the antenna.A measurable quantity that will be strongly affected from such dependence is the depolarization ratio [39]. It is defined in Raman spectroscopy (for linear excitation polarization) as the ratio between the intensity of the Raman field polarized orthogonal to the laser field (I ⟘ ) and the intensity of the Raman field polarized parallel to the laser field (I � ). The depolarization ratio provides information on the Raman polarizability tensor (α) of the vibration considered and is therefore a very useful tool.It was recognized early on that in SERS the relationship between the depolarization ratio and the components of the Raman polarizability tensor was not straightforward [3]. One striking example is provided by Fazio and coworkers, [38] where the polarized SERS intensity is found to be at a maximum in the direction orthogonal to the excitation field, whereas in Raman spectroscopy Abstract: The Raman depolarization ratio is a quantity that can be easily measured experimentally and offers unique information on the Raman polarizability tensor of molecular vibrations. In Surface Enhanced Raman Scattering (SERS), molecules are near-field coupled with optical nanoantennas and their scattering properties are strongly affected by the radiation patterns of the nanoantenna. The polarization of the SERS photons is consequently modified, affecting, in a non trivial way, the measured value of the SERS depolarization ratio. In this article we elaborate a model that describes how the SERS depolarization ratio is influenced by the nanoantenna re-radiation properties, sugg...

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Section: Introductionmentioning

confidence: 99%

On the SERS depolarization ratio

et al. 2015

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“…El empleo de nanoestructuras de plata presenta dos grandes ventajas, aparte de su actividad antimicrobiana: i) el fármaco se adsorbe fácilmente sobre ellas sin necesidad de funcionalización y se transportan juntos, y ii) debido a los plasmones localizados que soportan y que son resonantemente excitados por el láser a 532 nm que es la fuente de excitación de las técnicas espectroscópicas que utilizamos, se produce una intensificación de la fluorescencia (Surface Enhanced Fluorescence, SEF [5]) y/ó de la señal Raman (Surface Enhanced Raman Scattering, SERS [6,7]) del correspondiente fármaco que permite mayor sensibilidad en su detección, pudiéndose incluso llegar a utilizar dichas "señales" espectroscópicas intensificadas para obtener imágenes de distribución del sistema nanoportador-fármaco en la célula ó tejido "diana" [8].…”

Section: Introductionunclassified

Molecular characterization of drug´s nanocarriers based on plasmon-enhanced spectroscopy: Fluorescence (SEF) and Raman (SERS)

Sevilla¹,

Hernández²,

Corda

et al. 2013

Opt. Pura Apl.

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RESUMEN:Se presentan algunos resultados de la aplicación conjunta de las espectroscopías SERS (SurfaceEnhanced Raman Scattering) y SEF (Surface Enhanced Fluorescence) a la caracterización molecular de sistemas nanoportadores de los fármacos emodina, indometacina y ketorolaco, basados en el empleo de coloide de plata acuoso. En el caso del antitumoral emodina, el sistema "nanopartículas de plataemodina" se ha infiltrado posteriormente en silicio poroso, caracterizándose también el nuevo sistema. El análisis de los datos SERS, SEF y de absorción UV-Vis de indometacina y ketorolaco a diferentes valores de pH nos ha permitido, además, proponer los mecanismos correspondientes a la aproximación de las respectivas moléculas a la superficie de las nanopartículas de plata en el rango de pHs estudiados.Palabras clave: Raman, Fluorescencia, SERS, SEF, Emodina, Indometacina, Ketorolaco, Nanoportadores. ABSTRACT:The combined application of SERS (Surface-Enhanced Raman Scattering) and SEF (Surface Enhanced Fluorescence) to the molecular characterization of drug´s nanocarriers based on silver colloids is here shown for the antitumoral drug emodin, and the Non-Steroidal Anti-Inflammatory Drugs indomethacin and ketorolac. The system "silver nanoparticles-emodin" was subsequently embedded in porous silicon and the new system also characterized. The joint analysis of the SERS, SEF and UVVis spectra of indomethacin and ketorolac at different pHs has also allowed to propose schemes for the approaching mechanisms of the drug molecules to the silver nanoparticles surface in the pH range studied.

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“…where ψ n (x) = xj n (x) and ζ n (x) = xh (1) n (x) are Ricatti-Bessel functions, j n (x) and h (1) n (x) are the spherical Bessel functions, k 0 is wave number in vacuum, r 0 = a + ∆r is distance for an NP center to an emitter, and…”

Section: -3mentioning

confidence: 99%

“…[1][2][3][4][5] Till recently only photoluminescence enhancement by metal nanoparticles (NP) has been examined and many groups have experimentally demonstrated photoluminescence intensity enhancement for molecular and semiconductor emitters (Refs. 6-12 and Refs.…”

Section: Introductionmentioning

confidence: 99%

Plasmonic enhancement of electroluminescence

2018

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Here plasmonic effect specifically on electroluminescence (EL) is studied in terms of radiative and nonradiative decay rates for a dipole near a metal spherical nanoparticle (NP). Contribution from scattering is taken into account and is shown to play a decisive role in EL enhancement owing to pronounced size-dependent radiative decay enhancement and weak size effect on non-radiative counterpart. Unlike photoluminescence where local incident field factor mainly determines the enhancement possibility and level, EL enhancement is only possible by means of quantum yield rise, EL enhancement being feasible only for an intrinsic quantum yield Q0 < 1. The resulting plasmonic effect is independent of intrinsic emitter lifetime but is exclusively defined by the value of Q0, emission spectrum, NP diameter and emitter-metal spacing. For 0.1< Q0 < 0.25, Ag nanoparticles are shown to enhance LED/OLED intensity by several times over the whole visible whereas Au particles feature lower effect within the red-orange range only. Independently of positive effect on quantum yield, metal nanoparticles embedded in an electroluminescent device will improve its efficiency at high currents owing to enhanced overall recombination rate which will diminish manifestation of Auger processes. The latter are believed to be responsible for the known undesirable efficiency droop in semiconductor commercial quantum well based LEDs at higher current. For the same reason plasmonics can diminish quantum dot photodegradation from Auger process induced non-radiative recombination and photoionization thus opening a way to avoid negative Auger effects in emerging colloidal semiconductor LEDs.

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Metal-enhanced fluorescence

Cited by 207 publications

References 3 publications

On the SERS depolarization ratio

On the SERS depolarization ratio

Molecular characterization of drug´s nanocarriers based on plasmon-enhanced spectroscopy: Fluorescence (SEF) and Raman (SERS)

Plasmonic enhancement of electroluminescence

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