Plasmon oscillations frequency

Here p is the frequency of plasmon oscillations in a system of free electrons (3.7). The oscillator strengths ft introduced previously differ from the usual fm (see Section IV) in their normalization (Efl, / = 1). A method for calculating the thus defined oscillator strengths from experimental values of e2 is presented in Ref. 89. Since the energy range essential for collective oscillations is ho> < 30 eV, the electrons of inner atomic shells can be disregarded. Thus, the value of ne is determined by the density of valence electrons only, and only the transitions of these electrons should be taken into account in the sum over i in formula (3.15). A convenient formula for calculating the frequencies molecular liquids is presented in ref. 89 ... 

The near-infrared reflectance provides the response to plasmon oscillations of the electron gas (which are uniform excitations). This region of the spectrum is, however, not sensitive to the strength of the short-range coulombic interactions, which prevent conductivity in a Mott-Hubbard insulating state. This is illustrated by the frequency-dependent conductivity cx((o) measured in various salts exhibiting very different values of the conductivity at room temperature (Fig. 27). The peak of the conductivity at the frequency w0 correlates with the metallic character namely, a low frequency of the peak position corresponds to a high dc conductivity and vice versa. The structures below 0)o are attributed to the coupling with intramolecular modes. 

The plasma frequency corresponds to an oscillation as a whole of the electronic charge density with respect to the fixed ionic charge. By analogy with the phonon excitation, the corresponding excitation is called plasmon and it can be considered as the quantization of classical plasma oscillation. The plasmon oscillation is longitudinal with respect to its propagation and is comparable to the TO phonon mode. The macroscopic electric field associated... 

Mass-senstitive acoustic and optical transducers belong to the first group of sensors as depicted in Scheme 1. These sensors detect mass accumulation via a change in oscillation frequency, like the quartz crystal microbalance, or via a change in certain optical parameters, like the refractive index in surface plasmon resonance devices. 

Fig. 1.15. A schematic illustration of the excitation of the dipole surface plasmon oscillation by the electric field component of the light wave. The dipolar oscillation of the electrons has the same frequency as that of the incoming light wave...

Finally we recall that in real metals, plasmon oscillations occur not only at the plasma frequency cop but in every case when the... 

Collective oscillations of conduction electrons known as plasmons, have a characteristic resonance frequency cop which depends on the mass, density and charge of the carriers. If the incident light frequency matches the plasmon resonance frequency, a strong absorption and scattering cross-section is obtained. Metal... 

The observed conduction band splitting provides possible mechanism for the surface plasma generation of nanoclusters of noble metals such as Ag and Au with oscillation frequency that is dependent upon the dielectric constant, Zl, charge density, n, and effective mass of electron, m, in the surface skin. The plasmonic frequency can be derived as cOp = oc eEG /n/m as the real part of the... 

One source of EM enhancement may be attributed to the excitation of surface plasmons (SP) in the metal. A plasmon is a collective excitation in which all of the conduction electrons in a metal oscillate in phase. In the bulk, there is essentially only one allowed fundamental plasmon frequency. 

Following (9.27) we discussed the physical interpretation of the plasma frequency for a simple metal and introduced the concept of a plasmon, a quantized plasma oscillation. It may help our understanding of the physics of surface modes in small particles and the terminology sometimes encountered in their description if we expand that discussion. 

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])... 

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