Topic
Doppler broadening
About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.
Papers published on a yearly basis
Papers
More filters
25 May 2018
TL;DR: The Helmholtz-Zentrum Dresden-Rossendorf operates a superconducting linear accelerator for electrons with energies up to 35 MeV and average beam currents up to 1.6 mA with bunch charges up to 120 pC.
Abstract: The Helmholtz-Zentrum Dresden-Rossendorf operates a superconducting linear accelerator for electrons with energies up to 35 MeV and average beam currents up to 1.6 mA with bunch charges up to 120 pC. The electron beam is employed to produce several secondary beams including X-rays from bremsstrahlung production, coherent IR light in a Free Electron Laser, superradiant THz radiation, neutrons, and positrons. The secondary positron beam after moderation feeds the Monoenergetic Positron Source (MePS) where positron annihilation lifetime (PALS) and positron annihilation Doppler-broadening experiments in materials science are performed. The adjustable repetition rate of the continuous-wave electron beams allows matching of the pulse separation to the positron lifetime in the sample under study. The energy of the positron beam can be set between 0.5 keV and 20 keV to perform depth resolved defect spectroscopy and porosity studies especially for thin films. Bulk materials, fluids, gases, and even radioactive samples can be studied at the unique Gamma-induced Positron Source (GiPS) where an intense bremsstrahlung source generates positrons directly inside the material under study. A 22Na-based monoenergetic positron beam serves for offline experiments and additional depth-resolved Doppler-broadening studies complementing both accelerator-based sources.
63 citations
TL;DR: A protocol to estimate the solvent-induced broadening of electronic spectra based on a model that explicitly takes into account the environment embedding the solute, and results indicate that the broadenings computed with explicit and implicit models both follow the experimental trend.
Abstract: We present a protocol to estimate the solvent-induced broadening of electronic spectra based on a model that explicitly takes into account the environment embedding the solute. Starting from a classical approximation of the solvent contribution to the spectrum, the broadening arises from the spread of the excitation energies due to the fluctuation of the solvent coordinates, and it is represented as a Gaussian line shape that convolutes the vibronic spectrum of the solute. The latter is computed in harmonic approximation at room temperature with a time-dependent approach. The proposed protocol for the computation of spectral broadening exploits molecular dynamics (MD) simulations performed on the solute–solvent system, keeping the solute degrees of freedom frozen, followed by the computation of the excitation properties with a quantum mechanics/molecular mechanics (QM/MM) approach. The factors that might influence each step of the protocol are analyzed in detail, including the selection of the empirical f...
62 citations
TL;DR: In this article, the spectral absorption coefficients for combined Doppler and Lorentz broadening were calculated for a set of spectroscopic studies on flames. And the curves of growth were extended to cover the ranges of parameters which arise in spectroscopy studies of flames.
Abstract: Methods for the calculation of spectral absorption coefficients for combined Doppler and Lorentz broadening are summarized. The “curves of growth” have been extended to cover the ranges of parameters which arise in spectroscopic studies on flames.
62 citations
TL;DR: The spectral and spatial profiles of atomic hydrogen emission (the Balmer lines Hα and Hβ) from a low-pressure rf (13.56 MHz) discharge in H2+Ar mixtures have been studied as discussed by the authors.
Abstract: The spectral and spatial profiles of atomic hydrogen emission (the Balmer lines Hα and Hβ) from a low‐pressure rf (13.56 MHz) discharge in H2+Ar mixtures have been studied. The plasma emission was observed in a direction normal to the applied electric field. The Hα profiles exhibit central narrow components and wide components which are due to Doppler broadening. Comparisons of the Hα profiles in a pure hydrogen plasma with those in H2+Ar mixtures show that collisions of molecular hydrogen ions and hydrogen atoms with argon atoms play a significant role in the production of the Hα profile shapes.
62 citations
Proceedings Article•
16 Oct 2009TL;DR: Higher-order-mode excitation experiments are interesting because the anomalous dispersion region is shifted towards smaller wavelengths and because the existence of a cut-off wavelength generates spectral broadening only on the blue side of the pump wavelength as mentioned in this paper.
Abstract: Higher-order-mode excitation experiments are interesting because the anomalous dispersion region is shifted towards smaller wavelengths and because the existence of a cut-off wavelength generates spectral broadening only on the blue side of the pump wavelength.
62 citations