Search results for "rayleigh"
showing 10 items of 182 documents
Neutron polarizability and the n-e scattering length
1972
Abstract It is shown that the neutron polarizability contribution to the n-e scattering length is within the present level of precision. The experimental result on this interaction is consistent with a value of the neutron polarizability similar to the proton one.
Resonant Rayleigh scattering in quantum well structures
1996
Abstract We report continuous wave experiments on resonant Rayleigh scattering (RRS) performed on high quality GaAs AlGaAs quantum well structures. The simultaneous measurement of the resonant Rayleigh scattering and of the photoluminescence excitation (PLE) allows us to resolve very small differences between the two spectra. We show that, even in very good samples, there is a small but detectable Stokes shift of the RRS profile with respect to the PLE. It is also found that the RRS profile has a smaller linewidth and is sensitive to bound exciton transitions which are not detectable in the PLE. We compare our data with previous findings and discuss possible origins of the Stokes shift.
Three-dimensional point spread function of multilayered flat lenses and its application to extreme subwavelength resolution
2011
The three-dimensional (3D) point spread function (PSF) of multilayered flat lenses was proposed in order to characterize the diffractive behavior of these subwavelength image formers. We computed the polarization-dependent scalar 3D PSF for a wide range of slab widths and for different dissipative metamaterials. In terms similar to the Rayleigh criterion we determined unambiguously the limit of resolution featuring this type of image-forming device. We investigated the significant reduction of the limit of resolution by increasing the number of layers, which may drop nearly 1 order of magnitude. However, this super-resolving effect is obtained in detriment of reducing the depth of field. Li…
Teaching stable two-mirror resonators through the fractional Fourier transform
2009
We analyse two-mirror resonators in terms of their fractional Fourier transform (FRFT) properties. We use the basic ABCD ray transfer matrix method to show how the resonator can be regarded as the cascade of two propagation–lens–propagation FRFT systems. Then, we present a connection between the geometric properties of the resonator (the g parameters) and those of the equivalent FRFT systems (the FRFT order and scaling parameters). Expressions connecting Gaussian beam q-transformation with FRFT parameters are derived. In particular, we show that the beam waist of the resonator's mode is located at the plane leading to two FRFT subsystems with equal scaling parameter which, moreover, coincid…
Effects of Higher-Order Scattering in a Molecular Atmosphere
1964
The effects of higher-order scattering on intensity, degree of polarization, and direction of the plane of polarization in a molecular atmosphere have been calculated.Inclusion of higher-order scattering changes these parameters strongly. Particularly, consideration of higher-order scattering is essential in the blue wavelength range (large optical thickness). The influence increases with decreasing zenith distance of the sun. The earth albedo augments the effect, except for direction of the polarization, which is independent of higher-order scattering.
The Influence of Absorption on the Extinction of Solar and Sky Radiation
1965
The purpose of this paper is to investigate the influence of absorption of the aerosol particles on the extinction of solar and sky radiation. The efficiency factors have been computed as well as the extinction, the scattering, the absorption, and the scattering function for the whole turbid atmosphere with help of the Mie theory for a complex index of refraction for a more or less absorbent medium. From these values the intensities of diffuse sky radiation have been obtained. The extinction and absorption coefficients increase for a more absorbent atmosphere, whereas the scattering coefficient decreases. The imaginary part of the complex index of refraction effects an increasing attenuatio…
Coherent light scattering on nanofluids: computer simulation results.
2008
If coherent light is incident on a suspension containing nanoparticles, they act as scattering centers and the result of the far-field interference is a "speckled" image. The scattering centers have a complex movement of both sedimentation and Brownian motion. Consequently the speckle image is not static but presents time fluctuations. A computer code to simulate the dynamics of the coherent light scattering on nanofluids was written, tested, and used to calculate the far-field intensity variation for nanofluids having different particle size. The results are discussed and an alternative experimental method for fast nanoparticle size assessing is suggested as a possible application.
Intensity-Based Single Particle Plasmon Sensing.
2021
Plasmon sensors respond to local changes of their surrounding environment with a shift in their resonance wavelength. This response is usually detected by measuring light scattering spectra to determine the resonance wavelength. However, single wavelength detection has become increasingly important because it simplifies the setup, increases speed, and improves statistics. Therefore, we investigated theoretically how the sensitivity toward such single wavelength scattering intensity changes depend on the material and shape of the plasmonic sensor. Surprisingly, simple equations describe this intensity sensitivity very accurately and allow us to distinguish the various contributions: Rayleigh…
Sky radiation, polarization and twilight radiation in Greenland
1966
A) The measurements of the spectral radiances in the solar almucantar (scattering function) and the degree of polarization of the skylight in Greenland indicate the following: 1) The air near the surface of the ice cap of Northern Greenland is very pure. 2) The sky radiance however is different from the pure molecular (Rayleigh) atmosphere, the measured scattering function does not followRayleigh's law. 3) On the other hand the measured scattering functions cannot be explained satisfactoryly by scattering on the aerosols which have been measured near the surface. 4) Therefore the presence of a few particles per cm3 with radii in the range 0.10≤r≤1μ in heigher atmospheric layers has to be po…
An extended Ritz formulation for buckling and post-buckling analysis of cracked multilayered plates
2018
Abstract An extended Ritz formulation for the analysis of buckling and post-buckling behaviour of cracked composite multilayered plates is presented. The formulation is based on: (i) the First-order Shear Deformation Theory to model the mechanics of the multilayered plate; (ii) the von Karman’s theory to account for geometric non-linearities ; (iii) the use of an extended set of approximating functions able to model the presence of an embedded or edge crack and to capture the crack opening fields as well as the global behaviour within a single cracked domain. The numerical results of the buckling analyses and the equilibrium paths in the post-buckling regime are compared with the results fr…