نتایج جستجو برای: photon spectra
تعداد نتایج: 175255 فیلتر نتایج به سال:
We consider inelastic dark matter scenarios with photon mediator and a Higgs boson. The boson spontaneously breaks the gauge symmetry associated photon, gives mass to difference particles. Such can decay into particles hence be another source of at collider experiments. analyze sensitivity decays excited state charged FASER 2 experiment in fermion scalar scenarios. two spectra as illustrating e...
The synthesis, linear photophysical properties, two-photon absorption (2PA), excited-state transient absorption, and gain spectroscopy of a new fluorene derivative tert-butyl 4,4'-(4,4' (1E,1'E)-2,2'-(9,9-bis(2- (2-ethoxyethoxy)ethyl)-9H-fluorene-2,7-diyl)bis(ethene-2,1-diyl)bis(4,1 phenylene)]dipiperazine-1-carboxylate (1) are reported. The steady-state linear absorption and fluorescence spect...
The influence of quantum confinement on the one- and two-photon absorption spectra (1PA and 2PA) of PbS and PbSe semiconductor quantum dots (QDs) is investigated. The results show 2PA peaks at energies where only 1PA transitions are predicted and 1PA peaks where only 2PA transitions are predicted by the often used isotropic k x p four-band envelope function formalism. The first experimentally i...
Introduction Lead-based shields are the most widely used attenuators in X-ray and gamma ray fields. The heavy weight, toxicity and corrosion of lead have led researchers towards the development of non-lead shields. Materials and Methods The purpose of this study was to design multi-layered shields for protection against X-rays and gamma rays in diagnostic radiology and nuclear medicine. In this...
The scientific research regarding investigation, characterization and protection of the archeological specimens is manifested through a notable participation of multidisciplinary subjects and experts, scientists and archeometrists. One of the main principals which are considered by archaeometrists in the study of the precious specimens is the utilizing nondestructive methods. As an example, in ...
We have studied the intersubband resonance of GaAs=AlGaAs multi-quantum well systems by comparing photon drag and absorption spectra. The peak absorption at room temperature is found to be blueshifted from the photon drag resonance by as much as 33 cm−1. We argue that this di erence gives directly the depolarization shift. ? 2000 Elsevier Science B.V. All rights reserved.
The resonant multiple photon excitation of neutral niobium clusters using tunable infrared (IR) radiation leads to thermionic emission. By measuring the mass-resolved ionization yield as a function of IR wavenumber species selective IR spectra are obtained for Nb(n) (n = 5-20) over the 200-350 cm(-1) spectral range. The IR resonance-enhanced multiple photon ionization spectra obtained this way ...
We report a novel Fourier transform method for measuring two-photon excitation spectra. We demonstrate this method using simple dye molecules and discuss its applications in two-photon fluorescence microscopy and optimal control. This method facilitates an intuitive interpretation of recent control experiments in terms of tuning the nonlinear spectrum of the exciting laser source.
We instrumented a combined fluorescence spectroscopy and imaging system to characterize the single- and two-photon excited autofluorescence in epithelial tissue. Single-photon fluorescence (SPF) are compared with two-photon fluorescence (TPF) measured at the same location in epithelial tissue. It was found that the SPF and TPF signals excited at corresponding wavelengths are similar in nonkerat...
In this paper, we study gamma ray spectra for various scenarios of dark matter annihilation and decay. We focus on processes which generate only high-energy photons or leptons and photons, but no proton-antiproton pairs, to be compatible with PAMELA’s data. We investigate photons produced directly from two-body decay chains and photons produced together with charged particles. For the former ca...
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