نتایج جستجو برای: photon spectra
تعداد نتایج: 175255 فیلتر نتایج به سال:
The effects of the feedback of e+-e pair reinjection in a plasma due to photon photon absorption of its own radiation is examined. Under the assumption of euntinuous electron injection with a power law spectrum E-r and Compton losses only , it is shown that for r < 2 the steady state electron distribution function has a unique form independent of the primary injection spectrum. This electron di...
Electronic spectroscopy of nine benzannelated enediynes and a related fulvene was studied under one-photon and two-photon excitation conditions. We utilize measured absorbance and emission spectra and time-resolved fluorescence decays of these molecules to calculate their radiative lifetimes and fluorescence quantum yields. The fluorescence quantum yields for the other compounds were referenced...
In this study, the two-photon excited fluorescence spectra from cadmium selenide quantum dots (QDs) on a silicon nitride photonic crystal (PhC) membrane under femtosecond laser irradiation were investigated. These spectra can be fit to a tri-Gaussian function in which one component is negative in amplitude, and in which the Gaussian components with positive amplitude are assigned to exciton emi...
We study spectral gratings obtained as a result of two-photon excitation of the lowest electronic transition of several tetrapyrrole molecules with phase-locked pairs of femtosecond pulses. A particular dependence of these gratings on temperature indicates that mirror symmetry is present between two-photon absorption (TPA) and one-photon fluorescence spectra for non-centrosymmetrical chlorin, b...
We describe spontaneous parametric down-conversion of a single-photon pump in quadratic nonlinear waveguides and waveguide arrays, taking into account spectral broadening of the signal and idler photons. We perform a detailed analysis of the photon-pair intensities, spectra and spatial correlations for different types of phase-matching conditions and identify suppression of Rabi-like oscillatio...
The emission spectra for the spin-1 photon fields are computed when the spacetime is a (4+n)-dimensional Schwarzschild phase. For the case of the bulk emission we compute the spectra for the vector mode and scalar mode separately. Although the emissivities for the scalar mode is larger than those for the vector mode when n is small, the emissivities for the vector mode photon become dominant ra...
We present model calculations reproducing broadband spectra of γ-ray blazars by a relativistic leptonic jet, combining the EIC and the SSC model. To this end, the evolution of the particle distribution functions inside a relativistic pair jet and of the resulting photon spectra is investigated. Inverse-Compton scattering of both external (EIC) as well as synchrotron photons (SSC) is treated usi...
Inclusive transverse momentum spectra of charged particles in photoproduction events in the laboratory pseudorapidity range −1.2 < η < 1.4 have been measured up to pT = 8 GeV using the ZEUS detector. Diffractive and non–diffractive reactions have been selected with an average γp centre of mass (c.m.) energy of 〈W 〉 = 180GeV. For diffractive reactions, the pT spectra of the photon dissociation e...
Angle-dependent x-ray absorption near-edge structure ~XANES! and scanning photoelectron microscopy measurements were performed to differentiate local electronic structures at the tips and sidewalls of highly aligned ZnO nanorods. The overall intensity of the O K-edge XANES spectra is greatly enhanced for small photon incident angles. In contrast, the overall intensity of the Zn K-edge XANES is ...
Dilepton and photon production in heavy-ion collisions at SPS energies are studied in the relativistic transport model that incorporates self-consistently the change of hadron masses in dense matter. It is found that the dilepton spectra in proton-nucleus reactions can be well described by the conventional mechanism of Dalitz decay and direct vector meson decay. However, to provide a quantitati...
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