Surface Plasmon Radiation Research Articles

Angular dependence of roughness-assisted surface plasmon radiation: Comparison of theory and experiment

We present a calculation of the angular distribution of surface-plasmon radiation from a rough surface. The radiated fields are calculated to first order in the surface-roughness height $\ensuremath{\delta}$, and the results are compared with our earlier measurements. The present result is found to compare more favorably with experiment than a previous calculation by Kretschmann. The strength of the "backscattering" of surface plasmons from small surface features is determined and used to discuss certain features of the experimental results.

Observation of the simultaneous emission of roughness-coupled and optical-coupled surface plasmon radiation from silver

The optical excitation and decay of surface plasmons on Ag films is reported. The optical decay is observed as an annular cone of light when the substrate is in the form of a hemisphere. The polarization and angular distribution of this cone radiation is presented and compared to the roughness-coupled surface plasmon radiation simultaneously emitted from the Ag.

Some measurements of the angular distribution and polarization of surface plasmon radiation from Ag films

We present here measurements of the angular distribution of the radiation emitted in the decay of surface plasmons on Ag films. The radiation patterns have been measured in planes both parallel and perpendicular to the plane of incidence. Certain features of these patterns suggest that a scattering mechanism is present in the plasmon-photon conversion process that may be attributable to grain boundaries. A qualitative model is suggested for this grain boundary interaction in order to interpret the data. A brief comparison to the available theories is made.

Surface polaritons in a circularly cylindrical interface: Surface plasmons

A theoretical investigation of surface polaritons in the circularly cylindrical geometry is presented. The complete set of Maxwell's equations (retardation effects are not neglected) is solved with the simple dielectric function, $\ensuremath{\epsilon}(\ensuremath{\omega})=1\ensuremath{-}\frac{{\ensuremath{\omega}}_{p}^{2}}{{\ensuremath{\omega}}^{2}}$, where ${\ensuremath{\omega}}_{p}$ is the bulk plasma frequency. The resulting transcendental equation for the eigenfrequencies is solved via numerical methods for three representative values of the cylindricality constant, $\ensuremath{\alpha}=\frac{{\ensuremath{\omega}}_{p}a}{c}$, where $a$ is the cylinder radius and $c$ the velocity of light. In addition to the real nonradiative surface plasmons, various virtual radiative surface plasmons exist with properties depending rather strongly on $\ensuremath{\alpha}$. The results are compared with existing experimental data. Further experiments are proposed in order to reveal the most interesting features of the surface plasma modes.

Dispersion of Radiative Surface Plasmons in Aluminum Films by Electron Scattering

A 75-keV electron beam with a low angular divergence (8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$ rad) combined with a Wien filter spectrometer is used to examine the dispersion of radiative surface plasmons in thin oxidized aluminum films. The measurements agree with theory, provided the effect of the oxide layer is included.

Radiative Decay of Electron‐Induced Surface Plasmons in Rough Surfaces

AbstractCoupling between fast electron‐induced surface plasma waves in metals and an electromagnetic field was calculated for surfaces with statistical roughness. Measurements of electron‐induced surface plasmon radiation from evaporated silver targets (3.54 eV ≙ ≙ 350 nm peak wavelength) showed that a non Gaussian surface autocorrelation function must be assumed, which prefers medium spatial frequencies, and that the assumption of a plane surface for the surface plasmon excitation process is allowed if the surface is not too rough. With increasing roughness additionally lower frequency excitations take place. Agreement with the measured spectral distributions only could be obtained, if the optical constants of Philipp and Taft were used; from the optical constants of evaporated silver targets follows the peak intensity at 3.62 eV (λ = 342 nm), retardation taken into account.

Decay of non radiative surface plasmons into light on rough silver films. Comparison of experimental and theoretical results

The polarisation dependence of light emitted at different angles from the surface of thin silver films is measured. The experimental results are compared with theory. It is demonstrated that surface roughness is responsible for the light emission and not bulk inhomogeneities of the silver film.

Light emission from non radiative plasmons excited by electrons on smooth surfaces

Theoretical results are reported on the possibility to observe light emitted from the non radiative surface plasmons which are excited by fast electrons traversing a smooth vacuum-metal boundary. By covering the backside of the metal film with a medium of refractive indexn>1, light can be decoupled from the non radiative plasmons. In the angular intensity distribution this light has a strong characteristic peak exceeding the ordinary transition radiation by a factor of the order of 102.

Observed radiation from surface plasmons in aluminum

Plasma radiation from thin films of aluminum bombarded by non-normally incident 80 keV electrons has been investigated. Radiative decay of both volume plasmons and surface plasmons was observed with the surface plasmon radiation being very sensitive to contamination of the film surface by an oxide layer. The surface resonance occurs at 10.2 eV, whereas the volume resonance is at 15 eV. These values are in accord with electron energy-loss experiments.

Radiative surface plasmons in silver films

It is suggested that a new mode of radiative surface plasmons, recently considered by Agranovich, should be observable in the neighbourhood of the interband transition of silver, in the spectral region around 5 eV.

Radiative decay of electron induced surface plasmons

Discrimination between long wave bremsstrahlung and radiative surface plasmon decay (Ag targets) was possible due to different dependecies of the radiation intensity I on electron energy E. The observed I( E)-dependence may be explained. if only small wave vector surface plasmons are allowed to radiate.

Coupling between light and surface plasma-waves via non gaussian surface roughness

The surface structure autocorrelation function of evaporated thick silver layers contains quasiperiodic terms due to preferred sizes and distances of surface irregularities. This determines the angular dependence of the electron induced surface plasmon radiation.

Plasma resonance radiation from non radiative plasmons

Non radiative surface plasmons decay into photons on a rough surface. This light emission is studied with gold- and silver foils of different thicknesses. The surface plasmons are excited in this experiment by light. By this way a relatively accurate determination of the optical constants is possible.

"SIGNIFICANCE OF SURFACE PLASMONS FOR SURFACE STUDIES"

Radiative and non radiative surface plasmons and their dispersion curves. Excitation of these surface oscillations by electrons and by light. Applications : Sensitivity of the energy of the surface plasmons against surface contaminations. Measurement of surface roughness by means of the plasma radiation. Surface plasmons and reflectivity.

Notizen: Radiative Decay of Non Radiative Surface Plasmons Excited by Light

Notizen: Radiative Decay of Non Radiative Surface Plasmons Excited by Light