Showing papers on "Plasmon published in 1988"
TL;DR: The surface plasmon microscopy (SPM) method as mentioned in this paper uses plasmor surface polariton (PSP) fields instead of normal light as the illumination source, which can provide superior contrast without loss of spatial resolution.
Abstract: The imaging of low-contrast samples is a challenging task for optical measuring techniques, especially if high lateral resolution is also required. For example, a heterogeneously organized lipid monolayer transferred from the water surface to a solid substrate1 still needs an additional contrast enhancement mechanism (the solubility difference for a fluorescing chromophore incorporated between the fluid and the crystalline domains of the monolayer) to be visualized by fluorescence microscopy. The mere thickness or index contrast between the different regions is not sufficient to use either phase contrast or Nomarsky microscopy2 or the more recently developed Isoscope ellipsometer3. Here we describe a new microscope technique—surface plasmon microscopy (SPM)— which offers superior contrast without loss of spatial resolution by using plasmon surface polariton (PSP) fields instead of normal light as the illumination source. Such electromagnetic modes travel along a metal–dielectric interface as a bound, non-radiative surface wave, with its field amplitudes decaying exponentially perpen-dicular to the interface. Although photons can be converted into PSPs by means of a plasmon coupler (a grating or a prism in many cases) this 'light' differs considerably from plane electromagneticwaves4. PSPs are characterized by first, a pronounced disper-sion (energy and momentum are not linearly related by the speed of light); and second, a field intensity that is concentrated at the interface and strongly enhanced there. Some of these properties make these modes a sensitive measure of interfaces and ultrathin films. If plasmon surface polariton fields are used to illuminate interfacial structures in light microscopy, high contrast without loss of spatial resolution can be obtained owing to the high sensitivity of the plasmon resonance coupling to (for example) small optical thickness variations of thin dielectric coatings.
718 citations
TL;DR: An optical sensor based on the phenomenon of light-excited surface plasmon resonance has been investigated to measure liquid chemical concentrations in this article, where a white light source is used to excite surface PLASmon waves at a metal/analyte interface.
Abstract: An optical sensor based on the phenomenon of light-excited surface plasmon resonance has been investigated to measure liquid chemical concentrations. A white light source is used to excite surface plasmon waves at a metal/analyte interface. The wavelength of maximum absorption in the reflected light depends uniquely on the refractive index of the analyte.
168 citations
TL;DR: In this paper, the excitation and decay of surface plasmons at a silver-air interface using a time-resolved optical technique was studied and a momentum lifetime of 48 fs (13 \ensuremath{\mu}m) was found.
Abstract: We have studied the excitation and decay of surface plasmons at a silver-air interface using a time-resolved optical technique. Monitoring the surface-plasmon propagation enabled us to measure the dephasing of surface plasmons via their mean free path and a momentum lifetime of 48 fs (13 \ensuremath{\mu}m) was found. After a very rapid plasmon decay the energy is transferred into a strain wave and an increase in the temperature of the silver film. We have observed the acoustic phonons, associated with the strain, bouncing up and down the silver film and the heat diffusion on a picosecond time scale.
97 citations
TL;DR: In this paper, the acoustic plasmon branch present in the longitudinal spectrum of two spatially separated parallel quasi-two-dimensional conducting layers was investigated and the authors derived an exact expression for the group velocity in terms of the effective masses, densities and geometrical parameters of the heterostructure.
Abstract: We have investigated the acoustic plasma branch present in the longitudinal spectrum of two spatially separated parallel quasi-two-dimensional conducting layers. Our approach is based on the dielectric theory and is completely analytical within the random-phase approximation. By means of a systematic analysis we have obtained several exact results concerning the plasma dispersion relation. In particular, we have derived an exact expression for ${c}_{p}$ the acoustic plasmon group velocity in terms of the effective masses, densities and geometrical parameters of the heterostructure. We find that when the two layers are identical the system always admits a branch of acoustic plasmons as undamped modes for any finite value of the distance between the layers.
68 citations
TL;DR: Results confirm the strong anisotropy of the transition-metal-oxygen bonds with strong overlap in the basal plane related to the short bond lengths and much more ionic character along the tetragonal c axis.
Abstract: The temperature dependence of infrared reflection spectra of La/sub 2/NiO/sub 4/ single crystal in polarized light between 10 and 750 K is analyzed and compared to the results for an oriented sample of La/sub 2/CuO/sub 4/. In both compounds, the spectra are found to reflect the bi-dimensional character of this family of compounds with a plasmon restricted to the basal a-b plane. In the nickel compound, the plasma frequency increases with temperature according to a simple scheme of semiconducting behavior with thermal filling of an empty conduction band, consistent with the d/sup 8/ character of Ni. Conversely, in ''metallic'' La/sub 2/CuO/sub 4/ (d/sup 9/ character) the plasmon is found to shift little with temperature. The analysis of a number of results obtained with ceramics samples in superconducting and normal phases are reexamined under the light of these new data. The effective charges carried by the oxygen ions are also deduced from the splittings of polar modes into transverse and longitudinal components. Results confirm the strong anisotropy of the transition-metal-oxygen bonds with strong overlap in the basal plane related to the short bond lengths and much more ionic character along the tetragonal c axis.
67 citations
TL;DR: In this paper, the results of an experimental study of a totally symmetric prism/silver film/air gap/ silver film/prism system are presented in which both symmetric and antisymmetric surface plasmon-polaritons (SPP) are optically excited using 632·8 nm radiation.
Abstract: Results of an experimental study of a totally symmetric prism/silver film/air gap/silver film/prism system are presented in which both symmetric and antisymmetric surface plasmon-polaritons (SPP) are optically excited using 632·8 nm radiation. Data taken over a range of air gap thicknesses illustrate many interesting features in accordance with predictions made using Fresnel's equations. The manner in which the two coupled SPPs evolve in terms of Poynting vector distribution and electric field profiles within the structure is studied in detail. Both the transmitted and the reflected attenuated total reflection signals are investigated.
55 citations
TL;DR: In this paper, the application of plasmon surface polariton (PSP) fields to the characterization of thin films, e.g. Langmuir-Blodgett (LB) monolayers and multilayers, on solid substrates, is discussed.
49 citations
TL;DR: Calculations of the nonlinear optical behavior are developed for model composites consisting of nanospheres with a metallic core and a nonlinear shell suspended in a non linear medium, indicating that phase-conjugate reflectivity enhancements of 10(8) may be possible.
Abstract: Calculations of the nonlinear optical behavior are developed for model composites consisting of nanospheres with a metallic core and a nonlinear shell suspended in a nonlinear medium. The concept for the enhancement of optical phase conjugation from all these nonlinear regions is that the optical field can be concentrated both inside and in the neighborhood of the metallic core, aided by surface-mediated plasmon resonance. Calculations for gold cores and aluminum cores indicate that phase-conjugate reflectivity enhancements of 10(8) may be possible.
47 citations
TL;DR: In this paper, a quantum theory of plasmons in lateral multi-wire superlattices is presented, where the wires are electrically insulated from each other, and where weak electron tunneling between wires is allowed.
Abstract: We present a quantum theory of plasmons in lateral multiwire superlattices. Intersubband plasmons are studied in the quantum regimes where the wires are electrically insulated from each other, and where weak electron tunneling between wires is allowed. Our theory provides a plausible explanation of the experimentally observed infrared resonance in lateral multiwire superlattices in these regimes.
42 citations
TL;DR: In this paper, the growth of a thin SiC grown by chemical vapor deposition (CVD) of ethylene on Si(100) at 970 K was studied by x-ray photoelectron spectroscopy (XPS).
Abstract: The growth of a thin film of SiC grown by chemical vapor deposition (CVD) of ethylene on Si(100) at 970 K was studied by x‐ray photoelectron spectroscopy (XPS). The growth of the film was observed through the behavior of the Si(2p) and C(1s) core levels and their plasmon losses. A 1.2‐eV (towards higher binding energy) shift is observed for the Si(2p) binding energy between silicon in Si(100) and silicon in SiC. The plasmon loss energies measured as a function of film thickness below the C(1s) emission indicate that the C/Si ratio of the Si‐C film throughout the CVD process is fairly constant.
38 citations
Journal Article•
TL;DR: In this article, a theory of edge magnetoplasmons (EMP) propagation along the edge of a 2D-electron system in a magnetic field is presented, and an exact solution to the EMP problem at a sharp rectilinear boundary between two halfplanes with differing conductivities is obtained.
Abstract: Low frequency collective excitations-the so-called edge magnetoplasmons (EMP)-can propagate along the edge of a 2D-electron system in a magnetic field. In this paper, we construct from first principles a theory of EMP in various 2 0 systems (heterojunctions, MIS structures and electrons on the surface ofliquid helium). We obtain an exact solution to the EMP problem at a sharp rectilinear boundary between two half-planes with differing conductivities. In strong magnetic fields the EMP propagate in a narrow strip near the edge of the system, and are characterized by a gapless spectrum and anomalously weak attenuation. We work out an approximate method of solution for real structures in strong magnetic fields (e.g., for a system with a diffuse edge, for a strip and for a disk). We investigate EMP-like excitations of an inhomogeneous 2 0 system in the quantum Hall effect regime, and determine the EMP contribution to the response of a 2 0 system in an external AC electric field. Our results agree with experimental data.
TL;DR: In this article, the light emission from forward and reverse-biased sinusoidally structured Ag/n-GaAs Schottky diodes was investigated and a model explaining excitation and emission of surface plasmon polaritons was presented.
Abstract: We have investigated the light emission from forward‐ and reverse‐biased sinusoidally structured Ag/n‐GaAs Schottky diodes. Sinusoidally structured Schottky junctions show increased light emission because of the radiative decay of excited surface plasmon polaritons, resulting in drastically enhanced quantum efficiency. A model explaining excitation and emission of surface plasmon polaritons is presented.
TL;DR: In this paper, a multilayer assembly of cadmium arachidate deposited by the Langmuir-Blodgett (LB) dipping technique onto silver gratings was used to record the Raman spectrum of even a single monolayer.
Abstract: Plasmon surface polariton field‐enhanced Raman spectroscopy has been performed with multilayer assemblies of cadmium arachidate deposited by the Langmuir–Blodgett (LB) dipping technique onto silver gratings. The gain in sensitivity can be used to record the Raman spectrum of even a single monolayer. The quantitative analysis of the C‐H stretching region allows for the estimate of the tilt angle of the fatty salt molecules relative to the substrate normal. The extent of disorder in the LB films has been determined as a function of layer thickness, substrate conditions and temperature. By the investigation of monolayers of normal protonated CdA embedded into a matrix of multilayers of fully deuterated molecules we were able to monitor orientation and disorder locally resolved. Thus for the first time, it was possible to study the influence of the deposition process on the structural properties of underlying monolayers.
TL;DR: It is shown that in the a-b plane, there is a low-energy acoustic plasmon mode, in addition to the usual high-energy bulk plasMon, whichDepending as it does on electronic motion in the chains along the b axis, the frequency of the mode is highly anisotropic in theA- b plane.
Abstract: There is considerable evidence that the electronic behavior of orthorhombic ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ is dominated by energy bands associated with Cu-O sheets and chains. We discuss the long-wavelength plasmon modes expected in an array of parallel metallic sheets and chains, coupled by the Coulomb interaction and using the random-phase approximation. We show that in the a-b plane, there is a low-energy acoustic plasmon mode, in addition to the usual high-energy bulk plasmon. This new acoustic plasmon does not arise in an array of coupled layers or in an array of parallel chains. Depending as it does on electronic motion in the chains along the b axis, the frequency of the mode is highly anisotropic in the a-b plane.
TL;DR: In this paper, angle resolved electron energy loss spectroscopy (EELS) in reflection mode with low primary energy on a graphite single crystal was performed in off-Bragg-reflex geometry in two different directions within the (0001) surface plane.
12 Jul 1988
TL;DR: In this paper, the use of surface plasmon resonance measurements for the microscopical imaging of surfaces and thin films has been investigated and theoretical results for sensitivity optimization and focussed beam measurement are presented for scanned beam and plane-wave imaging of silver surfaces and superimposed dielectric layers.
Abstract: The use of surface plasmon resonance measurements for the microscopical imaging of surfaces and thin films has been investigated. Theoretical results are presented for sensitivity optimization and focussed beam measurement. Experimental results are presented for scanned beam and plane-wave imaging of silver surfaces and superimposed dielectric layers. Thickness sensitivity of about 3 angstroms has been achieved, with lateral resolution better than 20 microns.
TL;DR: In this paper, the authors present experimental results using high birefringence fiber which indicate two forms of polarising action, dependent on the parameters of the device, allowing selection of the polarisation transmitted.
Abstract: High-quality optical fibre polarisers based upon surface plasmon wave generation in a thin metal overlay have been reported recently. The letter presents experimental results using high birefringence fibre which indicate two forms of polarising action, dependent on the parameters of the device, allowing selection of the polarisation transmitted.
TL;DR: In this paper, the real and imaginary part of the complex surface plasmon wave vector were derived from the evanescent wave vector of the driving photon field on the Ag surface.
Abstract: Plasmon surface polaritons that are launched at an index step from a Ag/dielectric coating/air to a Ag/air interface interfere with the evanescent waves of the driving photon field. The resulting intensity distribution on the Ag surface can be imaged by the recently developed surface plasmon microscopy. We show that it is thus possible to derive the real part as well as the imaginary part of the complex surface plasmon wave vector.
TL;DR: In this paper, surface polaritons that are coherently launched at an index step interfere with the evanescent waves of the driving photon field and the resulting interference pattern can be analyzed by surface-plasmon microscopy and allows for the determination of the complex wave vector of the surface mode.
Abstract: Plasmon surface polaritons that are coherently launched at an index step interfere with the evanescent waves of the driving photon field. The resulting interference pattern can be analyzed by surface-plasmon microscopy and allows for the determination of the complex wave vector of the surface mode. Different interfaces are analyzed, and the results are compared with theoretical predictions.
TL;DR: In this article, the authors examined the use of surface plasmons to mediate the transport of molecular fluorescence across a corrugated thin metal film deposited onto a luminescent material.
Abstract: We examine the use of surface plasmons to mediate the transport of molecular fluorescence across a corrugated thin metal film deposited onto a luminescent material. We find that for a given wavelength component, the amount of fluorescence reradiated by the long‐range surface plasmon into a narrow angular range can be as large as ∼30% of that emitted isotropically into the medium above the sample in the absence of the metal layer.
TL;DR: In this article, a non-destructive optical means of determining the activated hole concentration in p-type polar semiconductors is described, where the Raman spectra from coupled plasmon-longitudinal-optical-phonon modes in five samples of Be−doped GaAs are measured and fitted using a theory which takes into account the degenerate light and heavy hole valence bands.
Abstract: A nondestructive optical means of determining the activated hole concentration in p‐type polar semiconductors is described. The Raman spectra from coupled plasmon‐longitudinal‐optical‐phonon modes in five samples of Be‐doped GaAs are measured and fitted using a theory which takes into account the degenerate light‐ and heavy‐hole valence bands. The results indicate that coupled plasmon‐longitudinal‐optical‐phonon modes in p‐type material differ both quantitatively and qualitatively from those in n‐type semiconductors.
TL;DR: quantitatively examining dispersion curves of surface plasmons along Ag, Al, Ni, and Fe films, it is found that the incidence angle theta(o) that produces a reflection minimum in a variety of ATR geometries is actually different from the angle theTA(p) that corresponds to the phase-matching condition.
Abstract: By quantitatively examining dispersion curves of surface plasmons along Ag, Al, Ni, and Fe films, we find that the incidence angle θo that produces a reflection minimum in a variety of ATR geometries is actually different from the angle θp that corresponds to the phase-matching condition. The difference between θp and θo is most significant in the Otto and Kretschmann geometries using metal films with large damping loss, such as Ni or Fe. In addition, we determine the angle θm at which maximum power density is coupled into the metal surface and show that in general the value of θm is also different from both θo and θp, the difference being again largest in the Otto or Kretschmann geometries. The differences between θo, θp, and θm are much smaller, but still detectable, in long-range surface plasmon and extended-range surface plasmon geometries. In all cases, the preferred incidence angle depends on whether one needs to optimize either the plasmon field composition or the power density in the metal.
TL;DR: The transient screening response in real space and time of the electron gas to a suddenly created point charge is calculated in the linear approximation, in a way which allows the decomposition of the response into a partDue to plasmons and a part due to electron-hole pairs.
Abstract: The transient screening response in real space and time of the electron gas to a suddenly created point charge is calculated in the linear approximation, in a way which allows the decomposition of the response into a part due to plasmons and a part due to electron-hole pairs. The results are expected to be qualitatively correct as a description of core-hole creation in simple metals in the limit of large photoelectron energies. We obtain a clear picture of an electronic ''shock wave'' which propagates outward from the core hole with some dispersion; the group velocities are centered at the Fermi velocity. Behind the shock wave is the static distribution plus a small ringing due to small-q plasmons. The results are examined in the light of experimental evidence for transient effects on core-hole decay.
TL;DR: In this paper, the authors used electron energy loss spectroscopy to investigate excitation processes in the band gap of the alkali fluorides and found that all the fluorides exhibit surface exciton losses and this observation is shown to be consistent with the model of Cox and Williams [Surface Sci.175 (1986) L782] for the surface loss.
TL;DR: In this paper, the application of high resolution electron energy loss spectroscopy (HREELS) to the study of space charge layers including Schottky barriers at semiconductor interfaces is discussed.
TL;DR: In this article, the dispersion of excitations in polycrystalline Pd, Ag, Cd and In by electron energy loss spectroscopy (EELS) was measured.
TL;DR: In this article, the nonequilibrium Green's function technique is applied to the electron-hole plasma in a semiconductor resonantly excited in the interband absorption region by a monochromatic laser.
Abstract: The nonequilibrium Green's function technique is applied to the electron-hole plasma in a semiconductor resonantly excited in the interband absorption region by a monochromatic laser. In contrast to earlier investigations the transverse electron-photon interband coupling is explicitly considered and the dynamical Stark effect between bands reflected by the appearance of additional laser induced gaps is taken into account. Starting from a unique quantum-mechanical description, a set of equations is given governing the spectrum and kinetics of electrons, holes, photons and plasmons (phonons) as well as the propagation of the Maxwell field. By a straightforward approximation for the self-energies and polarizations the system of equations beomes closed in the framework of a one-particle/mean-field description. However, the description is renormalized enough to describe many-particle effects as well as the nonlinear field behaviour in an arbitrary nonequilibrium situation.
TL;DR: In this paper, it was shown that the intrinsic satellites of photoelectrons are due to coupling to charge fluctuations being strongest for low onset (plasmon) energies, and that these broad plasmon satellites complicate the deconvolution, aside from containing a major fraction of the intensity.
TL;DR: In this paper, a Bethe-Salpeter equation describing the linear response of a semiconductor under plasma excitation was determined on the basis of a nonequilibrium Green's function technique.
Abstract: On the basis of a nonequilibrium Green's function technique we determine a Bethe-Salpeter equation describing the linear response of a semiconductor under plasma excitation. Dynamical correlations entering the effective screenede-h interaction are treated on the basis of the full RPA polarization function. Numerical results for optical gain and absorption spectra are presented for various temperatures and densities. The validity of the commonly used plasmon pole approximation with regard to the lineshape of optical spectra is critically investigated.