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Doppler broadening

About: Doppler broadening is a research topic. Over the lifetime, 5509 publications have been published within this topic receiving 92552 citations.


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TL;DR: In this article, the structure of nano-sized particles (clusters of solute atoms or Guinier-Preston-Bagaryatsky (GPB) zones) in aluminum alloys is investigated.

27 citations

Journal ArticleDOI
TL;DR: Stehle et al. as discussed by the authors analyzed Stark broadening of the lines corresponding to 2−n and 3−m transitions with principal quantum numbers n=7−12 and m=10−12 using recent model microfield method calculations.
Abstract: Spatially resolved measurements of deuterium Balmer and Paschen line emission have been performed in the divertor region of the National Spherical Torus Experiment using a commercial 0.5m Czerny-Turner spectrometer. While the Balmer emission lines, as well as the Balmer and Paschen continua in the ultraviolet and visible regions have been extensively used for tokamak divertor plasma temperature and density measurements, the diagnostic potential of infrared Paschen lines has been largely overlooked. We analyze Stark broadening of the lines corresponding to 2−n and 3−m transitions with principal quantum numbers n=7–12 and m=10–12 using recent model microfield method calculations [C. Stehle and R. Hutcheon, Astron. Astrophys., Suppl. Ser. 140, 93 (1999)]. Densities in the range (5–50)×1019m−3 are obtained in the recombining inner divertor plasma in 2–6MW neutral beam heated H-mode discharges. The measured Paschen line profiles show good sensitivity to Stark effects and low sensitivity to instrumental and Dop...

27 citations

Journal ArticleDOI
TL;DR: This work determines the absorption spectra of three aromatic molecules indole, pyridine, and benzene using time dependent density functional theory with several molecular dynamics sampling protocols: force-field based empirical potentials, ab initio simulations, and finally path-integrals for the inclusion of nuclear quantum effects.
Abstract: In this work, we examine the importance of nuclear quantum effects on capturing the line broadening and vibronic structure of optical spectra. We determine the absorption spectra of three aromatic molecules indole, pyridine, and benzene using time dependent density functional theory with several molecular dynamics sampling protocols: force-field based empirical potentials, ab initio simulations, and finally path-integrals for the inclusion of nuclear quantum effects. We show that the absorption spectrum for all these chromophores are similarly broadened in the presence of nuclear quantum effects regardless of the presence of hydrogen bond donor or acceptor groups. We also show that simulations incorporating nuclear quantum effects are able to reproduce the heterogeneous broadening of the absorption spectra even with empirical force fields. The spectral broadening associated with nuclear quantum effects can be accounted for by the broadened distribution of chromophore size as revealed by a particle in the box model. We also highlight the role that nuclear quantum effects have on the underlying electronic structure of aromatic molecules as probed by various electrostatic properties.

27 citations

Journal ArticleDOI
TL;DR: In this article, a treatment due to Kaulakys was used to estimate broadening and shift of 17 spectral lines of argon involving intermediate Rydberg states in the framework of impact theory.
Abstract: Results of experiments on low pressure broadening and shift of 17 spectral lines of argon involving intermediate Rydberg states are interpreted in the framework of the impact theory. Using a treatment due to Kaulakys it is shown that in pure argon and in the Ar-He mixture the experimental data are in satisfactory agreement with those calculated on the basis of the Fermi pseudopotential and polarization interaction. On the other hand, for the Ar-Ne mixture the theoretical broadening and shift values computed from this treatment are in poor agreement with experiment. The role of Maxwellian averaging as well as the scattering length in the analysis of the broadening cross-sections are also discussed.

27 citations

Journal ArticleDOI
TL;DR: In this article, the chemical vicinity of crystal defects in magnesium and magnesium-based alloys such as AZ31 was investigated with coincident Doppler broadening spectroscopy by comparing Mg-ion-irradiated AZ31 with Mg -ion-IRradiated Mg. No formation of solute-vacancy complexes was found due to the ion irradiation, despite the high defect mobility.
Abstract: Crystal defects in magnesium and magnesium-based alloys such as AZ31 are of major importance for the understanding of their macroscopic properties. We have investigated defects and their chemical surrounding in Mg and AZ31 on an atomic scale with Doppler broadening spectroscopy of the positron annihilation radiation. In these Doppler spectra, the chemical information and the defect contribution have to be thoroughly separated. For this reason, samples of annealed Mg were irradiated with Mg ions in order to create exclusively defects. In addition, Al- and Zn-ion irradiation on Mg samples was performed in order to create samples with defects and impurity atoms. The ion-irradiated area on the samples was investigated with laterally and depth resolved positron Doppler broadening spectroscopy and compared with preceding SRIM simulations of the vacancy distribution, which are in excellent agreement. The investigation of the chemical vicinity of crystal defects in AZ31 was performed with coincident Doppler broadening spectroscopy by comparing Mg-ion-irradiated AZ31 with Mg-ion-irradiated Mg. No formation of solute-vacancy complexes was found due to the ion irradiation, despite the high defect mobility.

27 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202331
202290
2021122
2020134
2019128
2018122