Showing papers on "Resonance published in 2006"
TL;DR: The dipole resonance is found to be very intense, and its peak wavelength is extremely sensitive to the height, edge length, and tip sharpness of the triangular nanoprism, which is the highest short-range refractive index sensitivity yet measured for a nanoparticle.
Abstract: The plasmonic properties of single silver triangular nanoprisms are investigated using dark-field optical microscopy and spectroscopy. Two distinct localized surface plasmon resonances (LSPR) are observed. These are assigned as in-plane dipolar and quadrupolar plasmon excitations using electrodynamic modeling based on the discrete dipole approximation (DDA). The dipole resonance is found to be very intense, and its peak wavelength is extremely sensitive to the height, edge length, and tip sharpness of the triangular nanoprism. In contrast, the intensity of the quadrupole resonance is much weaker relative to the dipole resonance in the single particle spectra than in the ensemble averaged spectrum. Several parameters relevant to the chemical sensing properties of these nanoprisms have been measured. The dependence of the dipole plasmon resonance on the refractive index of the external medium is found to be as high as 205 nm RIU-1 and the plasmon line width as narrow as ∼0.17 eV. These data lead to a sensin...
872 citations
TL;DR: In this article, the characteristics of a local plasmon resonance of a metal nanostructure exhibit several general properties under the quasistatic approximation, and the effect of optical gain on the Q factor is also obtained.
Abstract: Under the quasistatic approximation, the characteristics of a local plasmon resonance of a metal nanostructure exhibit several general properties. The resonance frequency depends on the fraction of plasmon energy residing in the metal through the real dielectric function of the metal. For a given resonant frequency, the Q factor of the resonance is determined only by the complex dielectric function of the metal material, independent of the nanostructure form or the dielectric environment. A simple result describing the effect of optical gain on the Q factor is also obtained.
490 citations
TL;DR: In this paper, the authors present simulations for a simple realistic site (one sedimentary layer over bedrock) characterized by a rather high impedance contrast and low quality factor, and investigate the link between H/V ratio peaks and the noise wavefield composition for the soil model considered here.
Abstract: SUMMARY Ambient vibration techniques such as the H/V method may have the potential to significantly contribute to site effect evaluation, particularly in urban areas. Previous studies interpret the so-called Nakamura’s technique in relation to the ellipticity ratio of Rayleigh waves, which, for a high enough impedance contrast, exhibits a pronounced peak close to the fundamental S-wave resonance frequency. Within the European SESAME project (Site EffectS assessment using AMbient Excitations) this interpretation has been tested through noise numerical simulation under well-controlled conditions in terms of source type and distribution and propagation structure. We will present simulations for a simple realistic site (one sedimentary layer over bedrock) characterized by a rather high impedance contrast and low quality factor. Careful H/V and array analysis on these noise synthetics allow an in-depth investigation of the link between H/V ratio peaks and the noise wavefield composition for the soil model considered here: (1) when sources are near (4 to 50 times the layer thickness) and surficial, H/V curves exhibit one single peak, while the array analysis shows that the wavefield is dominated by Rayleigh waves; (2) when sources are distant (more than 50 times the layer thickness) and located inside the sedimentary layer, two peaks show up on the H/V curve, while the array analysis indicates both Rayleigh waves and strong S head waves; the first peak is due to both fundamental Rayleigh waves and resonance of head S waves, the second is only due to the resonance of head S waves; (3) when sources are deep (located inside the bedrock), whatever their distance, H/V ratio exhibit peaks at the fundamental and harmonic resonance frequencies, while array analyses indicate only non-dispersive body waves; the H/V is thus simply due to multiple reflections of S waves within the layer. Therefore, considering that experimental H/V ratio (i.e. derived from actual noise measured in the field) exhibit in most cases only one peak, we conclude that H/V ratio is (1) mainly controlled by local surface sources, (2) mainly due to the ellipticity of the fundamental Rayleigh waves. Then the amplitude of H/V peak is not able to give a good estimate of site amplification factor.
434 citations
TL;DR: Studies of the resonance frequencies, amplitudes, linewidths, and line shapes as a function of microwave power, dc current, and magnetic field provide detailed new information about the exchange, damping, and spin-transfer torques that govern the dynamics in magnetic nanostructures.
Abstract: We demonstrate a technique that enables ferromagnetic resonance measurements of the normal modes for magnetic excitations in individual nanoscale ferromagnets, smaller in volume by more than a factor of 50 compared to individual ferromagnetic samples measured by other resonance techniques. Studies of the resonance frequencies, amplitudes, linewidths, and line shapes as a function of microwave power, dc current, and magnetic field provide detailed new information about the exchange, damping, and spin-transfer torques that govern the dynamics in magnetic nanostructures.
352 citations
TL;DR: The UV-visible spectra of the aqueous colloids show distinct bands corresponding to dipole and quadrupole plasmon modes, for diameters above 100 nm, in close agreement with predictions based on Mie theory.
Abstract: A modified seeded growth process has been used for the controlled synthesis of quasispherical, CTAB-stabilized gold nanoparticles from 12 up to 180 nm with narrow size distributions The UV-visible spectra of the aqueous colloids show distinct bands corresponding to dipole and quadrupole plasmon modes, for diameters above 100 nm, in close agreement with predictions based on Mie theory The assignment of the modes is demonstrated by calculation of near field enhancement maps based on the boundary element method Apart from other applications, since absorption is drastically reduced above 600 nm, while scattering is largely increased, these particles open new possibilities for construction of highly efficient photonic structures
351 citations
TL;DR: The results confirm the significant influence of the shell on the bubble dynamics: shell elasticity increases the resonance frequency by about 50%, and shell viscosity is responsible for about 70% of the total damping.
Abstract: A new optical characterization of the behavior of single ultrasound contrast bubbles is presented. The method consists of insonifying individual bubbles several times successively sweeping the applied frequency, and to record movies of the bubble response up to 25 million frames/s with an ultrahigh speed camera operated in a segmented mode. The method, termed microbubble spectroscopy, enables to reconstruct a resonance curve in a single run. The data is analyzed through a linearized model for coated bubbles. The results confirm the significant influence of the shell on the bubble dynamics: shell elasticity increases the resonance frequency by about 50%, and shell viscosity is responsible for about 70% of the total damping. The obtained value for shell elasticity is in quantative agreement with previously reported values. The shell viscosity increases significantly with the radius, revealing a new nonlinear behavior of the phospholipid coating.
342 citations
Book•
18 Apr 2006
TL;DR: In this article, the authors present a list of figures and tables for thermal cross sections and individual resonance properties, including properties of individual resonance parameters and their properties in terms of their properties.
Abstract: Preface Acknowledgements Contents List of Figures List of Tables 1. Thermal Cross Sections 2. Resonance Properties 3. Individual Resonance Parameters 4. Notation and Nomenclature Bibliography
314 citations
TL;DR: All resonances can be understood as plasmonic resonances of increasing order of the entire structure, and for an electrical field polarized parallel to the gap the so-called LC-resonance corresponds to the fundamental plAsmonic mode.
Abstract: We numerically study the spectral response of ‘U’-shaped split-ring-resonators at normal incidence with respect to the resonator plane. Based on the evaluation of the near-field patterns of the resonances and their geometry-dependent spectral positions, we obtain a comprehensive and consistent picture of their origin. We conclude that all resonances can be understood as plasmonic resonances of increasing order of the entire structure. In particular, for an electrical field polarized parallel to the gap the so-called LC-resonance corresponds to the fundamental plasmonic mode and, contrary to earlier interpretations, the electrical resonance is a second order plasmon mode of the entire structure. The presence of further higher order modes is discussed.
305 citations
TL;DR: The scattering spectra of single gold nanorods with aspect ratios between 2 and 4 have been examined and show that the longitudinal plasmon resonance (electron oscillation along the long axis of the rod) broadens as the width of the rods decreases from 14 to 8 nm, attributed to electron surface scattering.
Abstract: The scattering spectra of single gold nanorods with aspect ratios between 2 and 4 have been examined by dark field microscopy. The results show that the longitudinal plasmon resonance (electron oscillation along the long axis of the rod) broadens as the width of the rods decreases from 14 to 8 nm. This is attributed to electron surface scattering. Analysis of the data using γ = γbulk + AνF/Leff, where Leff is the effective path length of the electrons and νF is the Fermi velocity, allows us to determine a value for the surface scattering parameter of A = 0.3. Larger rods with widths of 19 and 30 nm were also examined. These samples also show spectral broadening, which is attributed to radiation damping. The relative strengths of the surface scattering and radiation damping effects are in excellent agreement with recent work on spherical gold nanoparticles by Sonnichsen et al., Phys. Rev. Lett., 2002, 88, 077402; and by Berciaud et al., Nano Lett., 2005, 5, 515.
281 citations
TL;DR: Electron spin resonance spectroscopy has been used to study the conduction electron spin resonance (CESR) of small silver particles stabilized in dehydrated Ag-rho zeolite and diameter of the stabilized particles was calculated based on the linewidth of CESR signal using Kawabata theory.
265 citations
TL;DR: In this article, the authors investigated four mechanisms that can affect the strength of the Wouthuysen-Field effect that were not previously considered, including photons redshifting into the Hi Lyman resonances, which may excite an H atom and result in a radiative cascade terminating in two-photon 2s 1 /2 → 1s 1/2 emission, rather than always degrading to Lyα as usually assumed.
Abstract: The first ultraviolet sources in the universe are expected to have coupled the H I spin temperature to the gas kinetic temperature via scattering in the Lyα resonance (the 'Wouthuysen-Field effect'). By establishing an Hi spin temperature different from the temperature of the cosmic microwave background, the Wouthuysen-Field effect should allow observations of H I during the reionization epoch in the redshifted 21-cm hyperfine line. This paper investigates four mechanisms that can affect the strength of the Wouthuysen-Field effect that were not previously considered. (1) Photons redshifting into the Hi Lyman resonances may excite an H atom and result in a radiative cascade terminating in two-photon 2s 1/2 → 1s 1/2 emission, rather than always degrading to Lyα as usually assumed. (2) The fine structure of the Lyα resonance alters the photon frequency distribution and leads to a suppression of the scattering rate. (3) The spin-flip scatterings change the frequency of the photon and cause the photon spectrum to relax not to the kinetic temperature of the gas but to a temperature between the kinetic and spin temperatures, effectively reducing the strength of the Wouthuysen-Field coupling. (4) Near line centre, a photon can change its frequency by several times the line width in a single scattering event, thus potentially invalidating the usual calculation of the Lyα spectral distortion based on the diffusion approximation. It is shown that (1) suppresses the Wouthuysen-Field coupling strength by a factor of up to ∼2, while (2) and (3) are important only at low kinetic temperatures. Effect (4) has a ≤3 per cent effect for kinetic temperatures T k ≥ 2 K. In particular, if the pre-reionization intergalactic medium was efficiently heated by X-rays, only effect (1) is important. Fitting formulae for the Wouthuysen-Field coupling strength are provided for the range of T k ≥ 2 K and Gunn-Peterson optical depth 10 5 < TOP < 10 7 so that all of these effects can be easily incorporated into 21-cm codes.
TL;DR: Magnetic metamaterials composed of 35 nm minimum feature-size gold split-ring resonators with a fundamental magnetic resonance at a wavelength of 900 nm are presented.
Abstract: We present magnetic metamaterials composed of 35 nm minimum feature-size gold split-ring resonators with a fundamental magnetic resonance at a wavelength of 900 nm. Corresponding calculations reveal excellent agreement with the experiments and show that the limits of size scaling have been reached.
TL;DR: In this article, a high resolution surface plasmon resonance sensor is proposed and demonstrated by measuring the plasman resonance enhanced Goos-Hanchen effect at attenuated total internal reflection.
Abstract: A high resolution surface plasmon resonance sensor is proposed and demonstrated by measuring the plasmon resonance enhanced Goos-Hanchen effect at attenuated total internal reflection The giant Goos-Hanchen shift results from the singular phase retardation at the resonance which leads to the superior sensitivity of the sensor
TL;DR: In this paper, the extinction spectra of spherical gold nanoparticles suspended in a homogeneous media were measured and the results were adjusted with Mie's theory together with an appropriate modification of the optical properties of bulk material considering the limitation that introduces the size of nanoparticles on the dielectric function.
Abstract: The extinction spectra of spherical gold nanoparticles suspended in a homogeneous media were measured and the results were adjusted with Mie's theory together with an appropriate modification of the optical properties of bulk material considering the limitation that introduces the size of nanoparticles on the dielectric function. Usually, the contribution of free electrons to the dielectric function is modified for particle size, while the contribution of bound electrons is assumed to be independent of size. This work discusses the separated contribution of free and bound electrons on the optical properties of particles and their variation with size for gold nanoparticles. The effects of dielectric function and its changes with size on extinction spectra near plasmon resonance are considered. The damping constant for free electrons was changed with size as usual and a scattering constant of C = 0.8 was used. For the bound electron contribution, two different models were analysed to fit the extinction spectra: on the one hand, the damping constant for interband transitions and the gap energy were used as fitting parameters and on the other, the electronic density of states in the conduction band was made size-dependent. For the first model, extinction spectra corresponding to particles with radius R = 0.7 nm were fitted using two sets of values of the energy gap and damping constant: Eg = 2.3 eV and or Eg = 2.1 eV and . For the second model, a simple assumption for the electronic density of states and its contribution to the dielectric function in terms of size allowed to adjust extinction spectra for all samples explored (from 0.3 to 1.6 nm radius). This last model uses only one parameter, a scale factor R0 = 0.35 nm, that controls the contribution of the bound electrons in nanoparticles. Contrast between the maximum and the minimum in the extinction spectra near the resonance at 520 nm or alternatively the broadening of the plasmon band can be used to determine the size of gold nanoparticles with radius smaller than 2 nm.
TL;DR: In this article, the authors measured -3.5 dB (8.1 dB corrected for losses) relative intensity squeezing between the probe and conjugate beams generated by stimulated, non-degenerate four-wave mixing in hot rubidium vapor.
Abstract: We have measured -3.5 dB (-8.1 dB corrected for losses) relative intensity squeezing between the probe and conjugate beams generated by stimulated, nondegenerate four-wave mixing in hot rubidium vapor. Unlike early observations of squeezing in atomic vapors based on saturation of a two-level system, our scheme uses a resonant nonlinearity based on ground-state coherences in a three-level system. Since this scheme produces narrowband, squeezed light near an atomic resonance it is of interest for experiments involving cold atoms or atomic ensembles.
TL;DR: In this article, a software package for solving partial-differential-equations (PDEs), as based on the finite element method (FEM), can be configured to calculate, efficiently, the frequencies and fields of the whisperinggallery (WG) modes of axisymmetric dielectric resonators.
Abstract: This paper explains how a popular, commercially-available software package for solving partial-differential-equations (PDEs), as based on the finite-element method (FEM), can be configured to calculate, efficiently, the frequencies and fields of the whispering-gallery (WG) modes of axisymmetric dielectric resonators. The approach is traceable; it exploits the PDE-solver's ability to accept the definition of solutions to Maxwell's equations in so-called `weak form'. Associated expressions and methods for estimating a WG mode's volume, filling factor(s) and, in the case of closed(open) resonators, its wall(radiation) loss, are provided. As no transverse approximation is imposed, the approach remains accurate even for quasi-transverse magnetic/electric modes of low, finite azimuthal mode order. The approach's generality and utility are demonstrated by modeling several non-trivial structures: (i) two different optical microcavities [one toroidal made of silica, the other an AlGaAs microdisk]; (ii) a 3rd-order sapphire:air Bragg cavity; (iii) two different cryogenic sapphire WG-mode resonators; both (ii) and (iii) operate in the microwave X-band. By fitting one of (iii) to a set of measured resonance frequencies, the dielectric constants of sapphire at liquid-helium temperature have been estimated.
TL;DR: In this article, high-statistics cross sections for the reactions {gamma}+p{yields}K{sup +}+{lambda} and {Gamma} +p{ yieldss} K{sup+} +{sigma}{sup 0} have been measured using CLAS at Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85
Abstract: High-statistics cross sections for the reactions {gamma}+p{yields}K{sup +}+{lambda} and {gamma}+p{yields}K{sup +}+{sigma}{sup 0} have been measured using CLAS at Jefferson Lab for center-of-mass energies W between 1.6 and 2.53 GeV, and for -0.85
TL;DR: Analysis of a suspended carbon nanotube used as a frequency mixer to detect its own mechanical motion shows that the nanotubes in these devices have no slack and that, by applying a gate voltage, the Nanotube can be tuned from a regime without strain to a regime where it behaves as a vibrating string under tension.
Abstract: We have used a suspended carbon nanotube as a frequency mixer to detect its own mechanical motion. A single gate-dependent resonance is observed, which we attribute to the fundamental bending mode vibration of the suspended carbon nanotubes. A continuum model is used to fit the gate dependence of the resonance frequency, from which we obtain values for the fundamental frequency, the residual and gate-induced tension in the nanotube. This analysis shows that the nanotubes in our devices have no slack and that, by applying a gate voltage, the nanotube can be tuned from a regime without strain to a regime where it behaves as a vibrating string under tension.
TL;DR: In this article, the authors studied resonant light scattering from single metal nanowires with diameters in the 100nm range and lengths of a few microns using synchrotron light.
Abstract: With infrared spectroscopic microscopy using synchrotron light, the authors studied resonant light scattering from single metal nanowires with diameters in the 100nm range and with lengths of a few microns. The Au and Cu nanowires were electrochemically grown in polycarbonate etched ion-track membranes and transferred on infrared-transparent substrates. Significant antennalike plasmon resonances were observed in good agreement with exact light-scattering calculations. The resonances depend not only on length and diameter but also on the dielectric surrounding of the nanowire. The observed maximum extinction at resonance corresponds to an electromagnetic far-field enhancement by a factor of about 5.
TL;DR: The micromagnetic simulation including the spin-transfer torque shows that the vortex core can be resonantly excited by an ac (spin-polarized) current through the dot and that the resonance frequency can be tuned by the dot shape.
Abstract: A magnetic vortex core in a ferromagnetic circular nanodot has a resonance frequency originating from the confinement of the vortex core. By the micromagnetic simulation including the spin-transfer torque, we show that the vortex core can be resonantly excited by an ac (spin-polarized) current through the dot and that the resonance frequency can be tuned by the dot shape. The resistance measurement under the ac current successfully detects the resonance at the frequency consistent with the simulation.
TL;DR: In this article, the optical properties of noble metal clusters are measured and compared in the size range 1.4-7 nm in diameter, and a complete theoretical description of these optical properties through the same semi-quantal model for the three metals is given.
Abstract: The optical properties of noble metal clusters are measured and compared in the size range 1.4–7 nm in diameter. The clusters of copper, silver and gold are produced by the same experimental technique, the deposition of preformed clusters in a transparent matrix. The size dependence is found to be different for the three metals. As the size decreases, the surface plasmon resonance is only slightly blue-shifted for silver, more strongly blue-shifted and damped for gold while this peak resonance vanishes for copper. We show that these results cannot be interpreted by a simple classical theory. Since ab initio calculations are not possible in this size range, we obtain a complete theoretical description of these optical properties through the same semi-quantal model for the three metals.
TL;DR: In this paper, the Gilbert damping constants of FeCoNi and CoFeB alloys with various compositions and half-metallic Co2MnAl Heusler alloy films prepared by magnetron sputtering were determined.
Abstract: We determined the Gilbert damping constants of Fe–Co–Ni and Co–Fe–B alloys with various compositions and half-metallic Co2MnAl Heusler alloy films prepared by magnetron sputtering. The ferromagnetic resonance (FMR) technique was used to determine the damping constants of the prepared films. The out-of-plane angular dependences of the resonance field (HR) and line width (ΔHpp) of FMR spectra were measured and fitted using the Landau–Lifshitz–Gilbert (LLG) equation. The experimental results fitted well, considering the inhomogeneities of the films in the fitting. The damping constants of the metallic films were much larger than those of bulk ferrimagnetic insulators and were roughly proportional to (g-2)2, where g is the Lande g factor. We discuss the origin of magnetic damping, considering spin–orbit and s–d interactions.
TL;DR: In this article, the energy shift induced by an off-resonant microwave field can be used to control spin oscillations by tuning the system either into resonance to achieve near-unity contrast or far away from resonance to suppress the oscillations.
Abstract: We study experimentally interaction-driven spin oscillations in optical lattices in the presence of an off-resonant microwave field. We show that the energy shift induced by this microwave field can be used to control the spin oscillations by tuning the system either into resonance to achieve near-unity contrast or far away from resonance to suppress the oscillations. Finally, we propose a scheme based on this technique to create a flat sample with either singly or doubly occupied sites, starting from an inhomogeneous Mott insulator, where singly and doubly occupied sites coexist.
TL;DR: In this paper, the spectral response of optical metamaterials consisting of gold split-ring resonators was studied using reflection spectroscopy in the near infrared region at normal incidence in the experiments.
Abstract: We study the spectral response of optical metamaterials consisting of gold split-ring resonators. We utilize reflection spectroscopy in the near infrared region at normal incidence in the experiments. Our theoretical modeling is based on rigorous diffraction theory. We perform a comprehensive analysis of the dependence of the features of both the electric and the oscillating-circuit resonance on the geometry of the metamaterial. We show that theory and experiment are in good agreement.
TL;DR: In this article, a scheme to design optical microcavities supporting high-Q$ modes with unidirectional light emission was introduced, which is achieved by coupling a low-Q-mode with unIDirectional emission to a high-q$ mode.
Abstract: We introduce a new scheme to design optical microcavities supporting high-$Q$ modes with unidirectional light emission. This is achieved by coupling a low-$Q$ mode with unidirectional emission to a high-$Q$ mode. The coupling is due to enhanced dynamical tunneling near an avoided resonance crossing. Numerical results for a microdisk with a suitably positioned air hole demonstrate the feasibility and the potential of this concept.
TL;DR: In this article, the authors present a theoretical model to predict the resonance frequency shift due to molecule adsorption on micro and nanocantilevers, and demonstrate that the effect of the adsorbate stiffness can be comparable or even larger than the mass effect, producing positive frequency shifts.
Abstract: The authors present a theoretical model to predict the resonance frequency shift due to molecule adsorption on micro- and nanocantilevers. They calculate the frequency shift experienced by cantilevers made of either silicon or the polymer SU-8, when two adsorbates, myosin protein and an alkanethiol, are attached to the cantilever surface. They demonstrate that the effect of the adsorbate stiffness can be comparable or even larger than the mass effect, producing positive frequency shifts. The results provide methods for decoupling both opposite effects and routes for the design of resonators with high sensitivity to molecule adsorption based on either stiffness or mass effects.
TL;DR: This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields.
Abstract: We report an approach for the detection of magnetic resonance imaging without superconducting magnets and cryogenics: optical atomic magnetometry. This technique possesses a high sensitivity independent of the strength of the static magnetic field, extending the applicability of magnetic resonance imaging to low magnetic fields and eliminating imaging artifacts associated with high fields. By coupling with a remote-detection scheme, thereby improving the filling factor of the sample, we obtained time-resolved flow images of water with a temporal resolution of 0.1 s and spatial resolutions of 1.6 mm perpendicular to the flow and 4.5 mm along the flow. Potentially inexpensive, compact, and mobile, our technique provides a viable alternative for MRI detection with substantially enhanced sensitivity and time resolution for various situations where traditional MRI is not optimal.
TL;DR: This is the first experimental observation of the combined effect of these two pathways on one particular two-photon transition, resulting in quantum-interference-modulated 2PA strength.
Abstract: We study two-photon absorption (2PA) in two series of new free-base porphyrins with 4-(diphenylamino)stilbene or 4,4'-bis-(diphenylamino)stilbene (BDPAS) attached via pi-conjugating linkers at the porphyrin meso-position. We show that this new substitution modality increases the 2PA cross section in the Soret band region (excitation wavelength 750-900 nm) of the core porphyrin by nearly 2 orders of magnitude, from sigma(2) approximately 10 GM for the meso-phenyl-substituted analogue to sigma(2) approximately 10(3) GM for the ethynyl-linked BDPAS-porphyrin dyad. The 2PA properties are quantitatively described by considering two different and interfering 2PA quantum transition pathways. The first path involves virtual transition via intermediate one-photon resonance. The second path bypasses the intermediate resonance and occurs due to a large permanent dipole moment difference between the ground and the final electronic states. To our best knowledge, this is the first experimental observation of the combined effect of these two pathways on one particular two-photon transition, resulting in quantum-interference-modulated 2PA strength.
TL;DR: In this article, the authors considered the distribution of dust that originates in the breakup of planetesimals that are trapped in resonance with a planet and showed that there are three distinct grain populations with different spatial distributions: (I) large grains have the same clumpy resonant distribution as the planeteimals; (II) moderate-sized grains are no longer in resonance and have an axisymmetric distribution; and (III) small grains are blown out of the system by radiation pressure and so have a density distribution that falls off as τ ∝ 1/r.
Abstract: This paper considers the distribution of dust that originates in the breakup of planetesimals that are trapped in resonance with a planet. It is shown that there are three distinct grain populations with different spatial distributions: (I) large grains have the same clumpy resonant distribution as the planetesimals; (II) moderate-sized grains are no longer in resonance and have an axisymmetric distribution; and (III) small grains are blown out of the system by radiation pressure and so have a density distribution that falls off as τ ∝ 1/r. Population III can be further divided into two subclasses: (IIIa) grains produced from population I that exhibit trailing spiral structure that emanates from the resonant clumps and (IIIb) grains produced from population II that have an axisymmetric distribution. Since observations in different wavebands are sensitive to different dust sizes, multiwavelength imaging of debris disks can be used to test models that explain the submillimeter structure of debris disks as due to resonant trapping of planetesimals. For example, a collisional cascade without blowout grains would appear clumpy in the submillimeter (which samples population I) and smooth at mid- to far-IR wavelengths (which sample population II). The wavelength of transition from clumpy to smooth structure is indicative of the mass of the perturbing planet. The size distribution of Vega's disk is modeled showing that the large quantities of population III grains detected recently by Spitzer must originate in the destruction of the grains seen in the submillimeter images. Thus, at high resolution and sensitivity the far- and mid-IR structure of Vega's disk is predicted to include spiral structure emanating from the submillimeter clumps.
TL;DR: The demonstration of strong resonance enhancement of a single high-order harmonic in the extreme ultraviolet (XUV) region generated from the interaction of a femtosecond pulse with low-ionized In ablation is reported.
Abstract: We report the demonstration of strong resonance enhancement of a single high-order harmonic in the extreme ultraviolet (XUV) region generated from the interaction of a femtosecond pulse with low-ionized In ablation. A strong 13th harmonic (61.2 nm) of Ti:sapphire laser radiation with output intensity almost two orders of magnitude higher than neighboring harmonics was observed in these studies. The high conversion efficiency of the 13th harmonic (8×10−5) is attributed to multiple collisions of electron trajectories with the origin due to multiphoton resonance with the In ion.