Coupled plasmon modes

Coupled plasmon modes have been observed experimentally in regularly spaced linear chains of gold nanoparticles [3.79] andin 2-D hexagonal arrays of silver nanoparticles [3.80]. The controlled propagation of plasmon excitations in tailored metal nanoparticle struc-... 

Coupled plasmon modes in an ordered hexagonal monolayer of metal nanoparticles A direct observation, Phys. Rev. Lett. 8A, 58A0-58A3 3.96... 

Simultaneously recorded STM topography (A) and photon map (B) of hexagonally ordered silver nanoparticles on a Au substrate. Scan area 26 X10 nm. Graph (C) shows a topography cross-section along the dotted line in (A). The emission intensity shows maxima when the tip is between the particles indicating that the emission is caused by coupled plasmon modes between the particles. 

In photoexcited polar semiconductors, the coherent LO phonons couple with photocarriers to form coherent LO phonon-plasmon coupled (LOPC) modes, which exhibit fundamentally different properties from those of bare phonons. Huber and coworkers revealed the ultrafast transition of an optical... 

Here, Ti, T2 and 02022 are the widths and resonance frequencies of the surface plasmon modes of the carbon cage, respectively [44] (the plasmons at the inner and outer surfaces are coupled oscillators and have two normal modes [59])... 

Decreasing the BWF component of the G-mode in nanotube water solution and in a film with organic molecules supports the assumption that coupling between plasmon modes and the G-mode is weaker in individual nanotubes and thin bundles than in thick bundles. 

Infrared active modes couple to the free carrier plasma and the energy of the coupled phonon-plasmon mode is sensitive to the electron density [3,20-22], In the range 1 x 1017 cm 3 < n < 1019 cm 3 the following approximation can be used for the free electron density as a function of the Ai(LO) mode frequency vmax [21] ... 

Fig. 17. The diffraction signal obtained from an identical PS pattern on Au and a glass surface, respectively. For the surface plasmon diffraction on Au and TIR diffraction on glass, the laser incident angle in both cases was set at 47° where the laser energy could be resonantly coupled into the surface plasmon mode.

Again, the mode spectrum depends on Zq. In the limit Zq -> 00, we obtain and = p/2, where describes the coupling of the 3D bulk and 2D plasmons deep in the medium (z 00), and, separately, a describes the decoupled, distant surface plasmon. However, in the limit z 0, we have col = and col = coyi + cay = col + o)2D where is now the decoupled bulk plasmon deep in the medinm, and, separately, describes the conpling of the surface plasmon with the 2D plasmon. For finite, nonvanishing Zq these hybridized plasmon modes are admixed as given by Eq.(31). 

In a heavily N-doped 6H sample (6xlOl9cm 3) Klein et al [34] observed an asymmetric broadening and a shift of the A,(LO) phonon which were attributed to the overdamped coupling between LO phonon and plasmon modes [35]. The interaction between these two excitations occurs via their macroscopic electric fields when the frequency of oscillation of a free-carrier plasma is close to that of the LO phonon. The dependence of the LO phonon-overdamped plasmon coupled modes on carrier concentration was reported by Yugami et al [36] in 3C-SiC films, where the carrier concentrations varied from 6.9 x 1016 to 2xl0,scm 3. They verified that the carrier concentrations obtained from RS were in fairly good agreement with the Hall measurement values, and that the Faust-Henry coefficient [35] for the 3C-SiC (C = + 0.35) was close to the value reported for 6H-SiC (C = + 0.39) [34]. 

In the i.r. range usually investigated (0.5-0.1 eV), besides the vibrational contributions of adsorbed species and multiphonon modes, plasmonic contributions associated with free electrons in the conduction band and defect excitations can also contribute, whose relative intensity is strongly influenced by the pretreatment conditions. In particular when the conduction band is extensively populated, the plasmonic modes couple with the vibrational ones (due to both adsorbed species and multiphonon lattice vibrations) causing a dramatic spectral modification and loss of any vibrational detail. 

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