Surface plasmons extinction

Figure 16.6 Tunability of the plasmon resonance maximum in gold nanostructures. Variation of the surface plasmon extinction maximum with (a) nanospheie diameter D (b) nanoshell total radius R2 with fixes R1/R2 = 0.857 (c) nanoshell core/shell ratio R1/R2 at fixed R2 = 70 nm (d) nanorod effective radius = (3V/4II) / at fixed aspect ratio R = A/B = 3.9 (e) nanorod aspect ratio R at fixed r ff = 11.43 nm. (Reproduced with permission firam P. K. Jain et al., 2006. J. Phys. Chem. B 110 7238-7248. Copyright 2006 American Chemical Society.)...

The same evolution of the absorption spectrum with the dose has been found in a high dose rate for various values of the Ag and Au ion fraction in the initial solution. Clusters Agi. Au are alloyed with the same composition. The maximum wavelength and the extinction coefficient Smax of the alloy depend on x. The experimental spectra are in good agreement with the surface plasmon spectra calculated from the Mie model at x values for which optical data are available (Fig. 12) [102]. Similar calculations were carried out for the alloy Ag Pdi obtained at a moderate dose rate [180]. 

As an example of extinction by spherical particles in the surface plasmon region, Fig. 12.3 shows calculated results for aluminum spheres using optical constants from the Drude model taking into account the variation of the mean free path with radius by means of (12.23). Figure 9.11 and the attendant discussion have shown that the free-electron model accurately represents the bulk dielectric function of aluminum in the ultraviolet. In contrast with the Qext plot for SiC (Fig. 12.1), we now plot volume-normalized extinction. Because this measure of extinction is independent of radius in the small size... 

Extinction calculations for aluminum spheres and a continuous distribution of ellipsoids (CDE) are compared in Fig. 12.6 the dielectric function was approximated by the Drude formula. The sum rule (12.32) implies that integrated absorption by an aluminum particle in air is nearly independent of its shape a change of shape merely shifts the resonance to another frequency between 0 and 15 eV, the region over which e for aluminum is negative. Thus, a distribution of shapes causes the surface plasmon band to be broadened, the... 

Another example listed in the table is graphite, the Frohlich mode of which is near 5.5 eV (2200 A) the boundaries of the negative e region are about 4 and 6.5 eV. The graphite surface plasmon has been tentatively identified as responsible for a feature in the interstellar extinction spectrum (see Section 14.5). 

Prominent extinction peak at 2170 A (5.7 eV) Surface plasmon in graphite... 

Byun KM, Kim S J, Kim D (2006) Profile effect on the feasibihty of extinction-based localized surface plasmon resonance biosensors with metallic nanowires. Appl Opt 45 3382-3389... 

Figure 34.1 Extinction (absorption) spectrum of gold nanorods and their transmitted electron microscopic image (inset). Cold nanorods (10 x 60 nm) showed peaks at 520 and 900nm corresponding to the transverse and longitudinal surface plasmon...

AuNPs in Liquid-State Environment Solute pure and monolayer-coated ( capped ) AuNPs are central targets in colloid and surface science also with a historical dimension [258-262]. Facile chemical syntheses introduced by Schmid et al. [260] and by Brust et al. [263] have boosted AuNP and other metal nanoparticle science towards characterization of the physical properties and use of these nanoscale metallic entities by multifarious techniques and in a variety of environments. Physical properties in focus have been the surface plasmon optical extinction band [264—269], scanning and transmission electron microscopy properties, and electrochemical properties of surface-immobilized coated AuNPs [173, 268-276], To this can be added a variety of AuNP crosslinked molecular and biomolecular... 

Jensen, T.R., Schatz, G.C., and Van Duyne, R.P. (1999) Nanosphere lithography surface plasmon resonance spectrum of a periodic array of silver nanopartides by ultraviolet-visible extinction spectroscopy and electrodynamic modeling. Journal of Physical Chemistry B, 103, 2394—2401. 

The optical properties of shapes other than spheres are generally more complex. If the metal nanocrystal is in the form of an ellipsoid or rod, then its surface plasmon frequency shifts drastically because the restoring force on the conduction electrons is extraordinarily sensitive to particle curvature [2]. For the general case of an ellipsoid, the extinction cross-section of a rod-like particle is given by... 

Fig. 14. Extinction spectra in different media (air, water and water-glycerol mixtures) for sintered opals made of Au Si02 particles with 15 nm core diameter and 225 nm total diameter. The corresponding refractive indices are indicated. The extinction spectrum consists of a surface plasmon mode from embedded gold particles and a weaker Bragg peak. The position of both modes is dependent upon solvent refractive index and (core and shell) particle volume fractions...

For silver complexed by CN , the surface plasmon spectrum of clusters develops with a maximum close to 395 nm, similar to that of hydrated clusters without ligand, but with a higher extinction coefficient per atom 395 (Ag cn") =... 

Absorption of and Emission fiom Nanoparticles, 541 What Is a Surface Plasmon 541 The Optical Extinction of Nanoparticles, 542 The Simple Drude Model Describes Metal Nanoparticles, 545 Semiconductor Nanoparticles (Quantum Dots), 549 Discrete Dipole Approximation (DDA), 550 Luminescence from Noble Metal Nanostructures, 550 Nonradiative Relaxation Dynamics of the Surface Plasmon Oscillation, 554 Nanoparticles Rule From Forster Energy Transfer to the Plasmon Ruler Equation, 558... 

The excitation of the surface plasmon is found to be an extinction maximum or transmission minimum. The spectral position v half-width (full width at half-maximum) T and relative intensity f depend on various physical parameters. First, the dielectric functions of the metal and of the polymer Cpo(v) are involved. Second, the particle size and shape distribution play an important role. Third, the interfaces between particles and the surrounding medium, the particle-particle interactions, and the distribution of the particles inside the insulating material have to be considered. For a description of the optical plasmon resonance of an insulating material with embedded particles, a detailed knowledge of the material constants of insulating host and of the nanoparticles... 

---