Surface plasmon dispersion relation for two component plasma spheres

The surface plasmon dispersion relation for a two component degenerate plasma system is obtained in spherical geometry, using the hydrodynamical model. The general solution for arbitrary value of angular quantum number l has been shown to have two branches, one of higher frequency and another of lower frequency. The formalism is explicitly applied to the case of electron-hole droplets (EHD) in silicon and germanium, and the normal mode frequencies have been computed for l = O, 1 and 2 values     

Surface plasmon dispersion relation for spherical metal particles

Using the hydrodynamical model, we have obtained the surface plasmon dispersion relation for spherical metallic particles in the following two cases: (1) a sharp surface cut off in electron density and (2) a diffused electron density at the surface. The diffused density is modelled with a step function. The diffuse nature of the electron density at surface of the metal particle is necessary to understand the experimental result for particles with small radii. Shift in the absorption frequency is estimated and found to be small.     

Surface plasmon THz waves on gratings

Because of their long propagation length at a metal surface in the far infrared, surface plasmons make potentially feasible the design and realization of 2D integrated terahertz systems over a metallic substrate. The coupling of a terahertz beam to the surface plasmon wave is very efficiently achieved by diffraction gratings engraved at the metal surface. In this article, we present a review of some recent works we performed in view of characterizing this coupling phenomenon. The analysis of the experimental data supplied by terahertz time-domain spectroscopy allows us to point out the main parameters that govern this diffraction process and the propagation of a surface plasmon over a flat or corrugated metal surface. To cite this article: M. Nazarov et al., C. R. Physique 9 (2008).     

Surface plasmon dispersion relation for normal and tangential modes

A theoretical investigation has been made for the surface plasmon dispersion relations for the case of normal and tangential modes to the surface. The hydrodynamical model has been used. We have obtained the dispersion relation by using the continuity of φ and dφ/dx, where φ is the scalar potential. The dispersion relations obtained in the present work have been successfully compared with the theoretical and experimental work of several authors.     

Non-linear flexural waves in thin layers

Non-linear flexural waves in thin plates or layers have been analyzed in this paper. The equation of motion of the plate is derived assuming that the motion is antisymmetric about the mid-plane of the plate and that the plate is thin. The plate is considered to be elastic. The Von Karman non-linear strains and Landau elastic constants have been used to model geometric and material non-linearities, respectively. An asymptotic analysis of wave motion is presented using the method of multiple scales. Evolution equations are derived for small amplitude traveling flexural elastic waves. Numerical results show waveform distortion, amplitude amplification, and harmonic generation.     

Surface plasmon dispersion relation of gold determined by MOM tunnel structures

The dispersion relation of surface plasma oscillations of the Au-vacuum interface was determined from the light emission of AlAl₂O₃Au tunnel diodes. The comparison of results with previous data obtained on Ag indicate that the mechanism of light generation is qualitatively the same for all MOM structures if the anode is one of the noble metals.     

Excitation by light ofω + andω − surface plasma waves in thin metal layers

Calculations with the extended Fresnel formulae show, thatω ₊ andω _? surface plasma waves can be excited by light, using the following optical arrangement: The metal foil is embedded between two dielectric layers of low index of refraction and equal thickness. Both sides of this 3-layer packet are in optical contact with a high index prism. Total reflection is broken byω ₊ andω _? resonances in reflectivity, transmission and absorption. Theω ₊ resonance is mainly transmissive, (transmission through a 800 Å thick silver foil greater than 50% at a wavelength of 5,461 Å) theω _? resonance is mainly absorptive. The polarization of the transmitted light exceeds 99%-theω ₊ resonance is proposed as a principle for a new optical polarizer.     

Laser melting of GaAs covered with thin metal layers

GaAs melting simulations with a pulsed ruby laser are reported. The presence of a thin metal layer deposited on the GaAs surface gives rise to a reduction in the melting threshold and to an increase of melted depths when compared with nude GaAs surfaces. Melting thresholds around 0.3 J/cm² for nude GaAs surface and slightly below 0.25 J/cm² for GaAs covered with a 120 Å tin layer are predicted in reasonable agreement with experimental results.     

Surface waves in thin layers of conducting media in the frequency range for the skin effect

The dispersion equation for a thin layer of a conducting medium in the frequency ranges for a pronounced skin effect is derived and analyzed. Cases of inertial, normal, and anomalous skin effects are considered. The dispersion equation and its solutions correspond to surface waves of a semi-infinite medium under conditions where the thickness of the layer greatly exceeds the skin depth. New mode spectra, which depend significantly on the thickness of the layer, are obtained in the opposite limit. Zh. Tekh. Fiz. 67, 83–85 (December 1997)     

Oxidation and annealing of thin FeTi layers covered with Pd

The hydrogen storage material FeTi has the disadvantage to lose its sorption capacity in contact with impurities such as O₂ and H₂O. A possibility to overcome this problem is to coat it with an anti-corrosive layer which is permeable for hydrogen. In this study we prepared FeTi layers covered with a (4 or 20 nm) thin Pd layer. We used ion beam and sputter profiling techniques, X-ray photoelectron spectrometry and scanning probe techniques to investigate the response of these bi-layers upon annealing up to 300°C in vacuum, air and 10⁻⁵ mbar O₂. The layered structure remains intact up to 150°C. At 200°C in air and O₂, Fe and (some) Ti move towards the Pd surface where they form oxide regions. At higher temperatures thicker oxide regions, presumably along the Pd grains, are formed. These processes are more pronounced for the case of 4 nm Pd. A model is presented to explain the observed phenomena. We conclude that up to 150°C 4 nm of Pd is sufficient to act as a protective layer. For a temperature of 200°C, 20 nm Pd may still provide sufficient protection against oxidation.     

Surface plasmon attenuation by thin film overlayers in the far infrared

The attenuation of far infrared (λ = 119 μm) surface plasmons propagating in thin films coated onto metal substrates is calculated. Faster than linear increases with thickness h for h ? 1 μm are predicted from solutions of the dispersion relations, in agreement with previously unexplained experimental results [Schlesigner et al., Solid State Comm. $\text{39}$, 1035 (1981)].     

Surface plasmon resonance from metallic columnar thin films

Surface plasmon (SP) waves on the interface of a dielectric (such as water) and a metallic columnar thin film (CTF) of porosity as high as 0.55 were experimentally and theoretically investigated. The CTFs were made of Al, Au, Ag, or Cr. As the porosity increases, the SP resonance (SPR) dip was found to widen, shift to higher wave numbers, and become asymmetric due to increasing scattering losses. With further increase of porosity, the SPR dip was found to disappear, leaving behind only a peak near the onset to the total internal reflection regime. The shape of the nanoislands constituting the CTF is better described as ellipsoidal than as spherical or spheroidal, indicating thereby the existence of orientational biaxial anisotropy even for CTFs thinner than 60 nm. For a best fit between the theoretical calculations and the experimental data, the CTF was divided into two layers having different porosity and nanoisland shape, particularly for the Ag- and Au-CTFs. The sensitivity of the CTF-based SPR signal to refractive index variations of an analyte infiltrating the nanopores of and in the region adjoining the metallic CTF was found to be doubly enhanced compared to that for the SPR signal from a nonporous metallic film.     

Resonance dispersion of the longitudinal waves in disperse composites

Vibrations and longitudinal waves in a composite formed by a viscoelastic matrix and solid-state inclusions are considered. Vibration-wave processes in the long-wave approximation are described on the basis of the complex dynamic density taking into account inertial-elastic-viscous interaction of the matrix and inclusion-oscillators upon their forward vibrations. Resonance dependences for the dynamic density and translational viscosity of the composite at the moderate volume concentration of inclusions are presented. The formulas obtained are specified for composites with spherical and cylindrical inclusions and are compared with the known experimental results.     

Long-range surface plasmon polaritons at THz frequencies in thin semiconductor layers

We present a theoretical investigation of THz long-range surface plasmon polaritons propagating on thin layers of InSb.The metallic behavior of doped semiconductors at THz frequencies allows the excitation of surface plasmon polaritons with propagation and confinement lengths that can be actively controlled.This control is achieved by acting on the free carrier density,which can be realized by changing the temperature of InSb.