Peak plasmon resonant scattering

Figure 4. Effect of silver particle s shape on the peak plasmon resonance scattering wavelength. Reproduced from [14] with permission from the publisher.

Figure 3. Calculated extinction (black), absoiption (dark grey), and scattering (Ggbt grey) cross section as a Auction of wavelength for a 20,40,80, and 120 nm diameter gold particle in water. As the particle diameter is increased, the plasmon resonance scattering peak shifts to loiiger wavelengths and beconre broader.

LSPs are detected as resonance peaks in the absorption or scattering spectra or as dips in the transmission spectra of the metallic nanoparticles. Nanoparticles of very conductive metals like gold, silver, and copper are ideal materials for excitation of localized surface plasmons due to an extremely high ratio of the modulus of the real (Sr) to the imaginary parts (8i) of its dielectric constant. Silver and copper nanoparticles are prone to oxidation and therefore often require coatings of protective over layers. Gold nanoparticles are chemically stable and are employed for the development of devices based on plasmon resonances of nanoparticles. 

Kotler and Nitzan" applied the electrostatic limit to a silver sphere coated with a dye. They found also in this case a double-peak behavior, under certain circumstances. Noteworthy, are the enhancements of the Raman scattering of up to —10", near the particle plasmon resonance. (For their model of a sphere it is at 3.5 eV but for other shapes it can be brought into the visible range). The enhancement is very weakly dependent on the distance from... 

Figure 15.1 illustrates the extinction, absorption, and scattering results from sample calculations performed for a common-sized nanoshell with a core diameter of 260 nm and a shell thickness of 20 nm immersed in water. The extinction peak observed in Fig. 15.1 is also known as the plasmonic resonance of the nanoshell. Plasmon is a result of the oscillation of incompressible electron gas molecules in the conducting gold shell. Such resonance can effectively alter the interference pattern... 

According to Van Duyne et al. [43,44], in order to obtain SER spectra with enhancement factors as large as possible, the excitation and scattering wavelengths should, if possible, sit at the two sides of a surface plasmon resonance extinction peak [43,44]. In addition, the excitation wavelength can be selected corresponding to the molecular absorption, and... 

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