Search results for "continuum"
showing 10 items of 477 documents
Spectral anomalies in supercontinuum focused waves
2006
The diffraction-induced spectral anomalies in the focal plane of an apertured spherical wave with supercontinuum flat-top power spectrum are investigated. Coherent broadband radiation (also incoherent white light) demonstrates a strong blue shift in the vicinity of the optical axis, and discrete spectral gaps with overall red shift arise out of this central region. Unlike narrow-band light, the spectral switch effect fades away with ultra-broad spectra.
Phototransition of Na(3p3/2) into high Rydberg states and the ionization continuum
2005
A model potential method is used to investigate photoabsorption from the Na(3p3/2) state. Absorption cross sections into higher Rydberg states and photoionization cross sections are presented as an analytical function of photo electron energy. Einstein coefficients for spontaneous emissions 3p3/2 ← ns1/2, nd5/2, nd3/2 are tabulated for n up to 50. The Einstein coefficients and low-energy ionization cross sections are believed to be accurate to better than 2–3%, above 1 eV the error may increase to 4–6%.
Continuum and discrete excitation spectrum of single quantum rings
2005
Photoluminescence and excitation of the photoluminescence spectroscopy has been performed in single InGaAs self-assembled quantum rings embedded in a field effect structure device. To determine their electronic structure, bias-dependent optical transitions have been analyzed both, for individual quantum rings, and for the averaged ensemble. Our results are compared with a theoretical model, and also with results reported by other authors studying similar nanostructures.
New VR magnification ratios of QSO 0957+561
2004
We present VR magnification ratios of QSO 0957+561, which are inferred from the GLITP light curves of Q0957+561A and new frames taken with the 2.56m Nordic Optical Telescope about 14 months after the GLITP monitoring. From two photometric approaches and a reasonable range for the time delay in the system (415-430 days), we do not obtain achromatic optical continuum ratios, but ratios depending on the wavelength. These new measurements are consistent with differential extinction in the lens galaxy, the Lyman limit system, the damped Ly-alpha system, or the host galaxy of the QSO. The possible values for the differential extinction and the ratio of total to selective extinction in the V band …
Spin eigenexcitations of an antiferromagnetic skyrmion
2019
We theoretically predict and classify the localized modes of a skyrmion in a collinear uniaxial antiferromagnet and discuss how they can be excited. As a central result, we find two branches of skyrmion eigenmodes with distinct physical properties characterized by being low or high energy excitations. The frequency dependence of the low-energy modes scales as $R_0^{-2}$ for skyrmions with large radius $R_0$. Furthermore, we predict localized high-energy eigenmodes, which have no direct ferromagnetic counterpart. Except for the breathing mode, we find that all localized antiferromagnet skyrmion modes, both in the low and high-energy branch, are doubly degenerated in the absence of a magnetic…
Coincidence Electron Scattering (e, e′c) in the Giant Resonance Region of 28Si
1986
In the nuclear continuum region, the inherent power of inelastic electron scattering to map out the Fourier transforms of the transition charge and current densities is completely exploited only if the inelastically scattered electron is detected in coincidence with a nuclear decay product c. The coincidence requirement effectively eliminates the strong elastic radiative tail which hitherto plagued the analysis of single arm (e,e′) experiments.
An energy residual-based approach to gradient effects within the mechanics of generalized continua
2012
AbstractGeneralized continua exhibiting gradient effects are addressed through a method grounded on the energy residual (ER)-based gradient theory by the first author and coworkers. A main tool of this theory is the Clausius-Duhem inequality cast in a form differing from the classical one only by a nonstandard extra term, the (nonlocality) ER, required to satisfy the insulation condition (its global value has to vanish or to take a known value). The ER carries in the nonlocality features of the mechanical problem through a strain-like rate field, being the specific nonlocality source, and a concomitant higher-order long-range stress (or microstress) field. The thermodynamic restrictions on …
Radio emission of SN1993J: the complete picture. I. Re-analysis of all the available VLBI data
2010
We have performed a complete re-calibration and re-analysis of all the available VLBI observations of supernova SN1993J, following an homogeneous and well-defined methodology. Observations of SN1993J at 69 epochs, spanning 13 years, were performed by two teams, which used different strategies and analysis tools. The results obtained by each group are similar, but their conclusions on the supernova expansion and the shape and evolution of the emitting region differ significantly. From our analysis of the combined set of observations, we have obtained an expansion curve with unprecedented time resolution and coverage. We find that the data from both teams are compatible when analyzed with the…
The Nature of Soft Excess in ESO 362-G18 Revealed by XMM-Newton and NuSTAR Spectroscopy
2021
We present a detailed spectral analysis of the joint XMM-Newton and NuSTAR observations of the active galactic nuclei (AGN) in the Seyfert 1.5 Galaxy ESO 362-G18. The broadband ($0.3\mbox{--}79$ keV) spectrum shows the presence of a power-law continuum with a soft excess below $2$ keV, iron K$\alpha$ emission ($\sim 6.4$ keV), and a Compton hump (peaking at $\sim 20$ keV). We find that the soft excess can be modeled by two different possible scenarios: a warm ($kT_\mathrm{e}\sim0.2$ keV) and optically thick ($\tau\sim34$) Comptonizing corona; or with relativistically-blurred reflection off a high-density ($\log{[n_\mathrm{e}/\mathrm{cm}^{-3}]}>18.3$) inner disk. These two models cannot be e…
Abelian projection and studies of gauge-variant quantities in lattice QCD without gauge fixing
1996
We suggest a new (dynamical) Abelian projection of the lattice QCD. It contains no gauge condition imposed on gauge fields so that Gribov copying is avoided. Configurations of gauge fields that turn into monopoles in the Abelian projection can be classified in a gauge invariant way. In the continuum limit, the theory respects the Lorentz invariance. A similar dynamical reduction of the gauge symmetry is proposed for studies of gauge-variant correlators (like a gluon propagator) in lattice QCD. Though the procedure is harder for numerical simulations, it is free of gauge fixing artifacts, like the Gribov horizon and copies.