Metallic nanoparticles localized surface plasmon resonance

Van Duyne RP, Haes AJ, Zou S, Schatz GC (2004) A Nanoscale Optical Biosensor The Long Range Distance Dependence of the Localized Surface Plasmon Resonance of Noble Metal Nanoparticles. J Phys Chem B 108 109-116... 

Localized surface plasmon resonance (LSPR) at the metal surface has been exploited to enhance the signal obtained from optical biochips and thereby lower the limits of detection. There are two main enhancement factors (i) an increase in the excitation of the fluorophore by localizing the optical field on the nanoparticles near the fluorophore and (ii) an increase in quantum efficiency of the fluorophore. The plasmon resonance wavelength should coincide with the fluorophore absorption band to obtain the maximum emission efficiency. Several parameters concerning the signal detection enhancement are as follows (84)... 

Haes, A.J. Zou, S. Schatz, G..C. Van Duyne, R.P. (2004) Nanoscale optical biosensor Short range distance dependence of the localized surface plasmon resonance of noble metal nanoparticles. Journal of Physical Chemistry B 108 6961-6968. 

Metal nanoparticles have attracted considerable interest due to their properties and applications related to size effects, which can be appropriately studied in the framework of nanophotonics [1]. Metal nanoparticles such as silver, gold and copper can scatter light elastically with remarkable efficiency because of a collective resonance of the conduction electrons in the metal (i.e., the Dipole Plasmon Resonance or Localized Surface Plasmon Resonance). Plasmonics is quickly becoming a dominant science-based technology for the twenty-first century, with enormous potential in the fields of optical computing, novel optical devices, and more recently, biological and medical research [2]. In particular, silver nanoparticles have attracted particular interest due to their applications in fluorescence enhancement [3-5]. 

For centuries, metal nanoparticles have never ceased to attract scientists and artists from many diverse cultures. In this section we briefly introduce a phenomenon of metal nanoparticles that still inspires scientists localized surface plasmon resonance (LSPR) (Hutter and Fendler, 2004). Metal nanoparticles show nonlinear electronic transport (single-electron transport of Coulomb blockade) and nonlinear/ultrafast optical response due to the SPR. Conduction electrons (—) and ionic cores (-F) in a metal form a plasma state. When external electric fields (i.e., electromagnetic waves, electron beams etc.) are applied to a metal, electrons move so as to screen perturbed charge distribution, move beyond the neutral states, return to the neutral states, and so on. This collective motion of electrons is called a plasma oscillation. SPR is a collective excitation mode of the plasma localized near the surface. Electrons confined in a nanoparticle conform the LSPR mode. The resonance frequency of the surface plasmon is different... 

Metal-based nanomaterials have been regarded as the most widely and deeply studied photothermal agents. The metal nanoparticles exhibit excellent localized surface plasmon resonance (LSPR) properties, caused by nanoscale oscillations of free electrons on the surface of metal particles. The intriguing LSPR property makes metal nanoparticles absorb light in visible and NIR regions and convert the optical energy to heat. This characteristic of metal nanoparticles has greatly motivated the research on metal-based... 

The enormous popularity of GNRs in recent years can be attributed not only to the ease and general reproducibility of the synthesis conditions, but also to their intense and wavelength-tunable optical properties. These are intimately associated with surface plasmons, which are bounded by nanoscale dimensions and resonate at specific electromagnetic frequencies. These localized surface plasmon resonances (LSPRs) are highly sensitive to particle size, shape, material composition, and the local dielectric environment. A number of recent monographs and reviews provide a detailed discussion on the many factors that significantly impact the LSPR of metal nanoparticles. ... 

Metal nanoparticles present localized surface plasmon resonances (LSPRs) that are collective excitations of the electrons at the interface between a conductor and a dielectric. The resonant plasma oscillation causes local field enhancement, and this is utilized in SERS [61,62], second-harmonic generation [63], and scanning near-field optical microscopy [64]. In particular, certain metals such as silver and gold have been much studied due to the feet that they present this LSPR in the visible spectral region. 

As discussed in previous sections, plasmonic structures improve the absorption efficiency of the photovoltaic absorber layers by preferentially scattering [40] and exciting localized surface plasmons [12, 41] or plasmon polaritons [42-46]. Surface plasmons are localized by noble metallic nanoparticles (NPs) such as Cu [47-49], Ag and Au resulting in localized surface plasmon resonance (LSPR). Ag and Au NPs are the most widely used materials due to their surface plasmon resonances located in the visible range. A1 and Cu, which have resonance in the ultraviolet and... 

---