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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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Journal ArticleDOI
TL;DR: In this article, the authors used high power pulsed tunable dye laser to measure plasma ion temperatures and found that the fluorescence linewidth of room temperature ions broadens from 1.50 to 2.87 GHz when the homogeneous laser intensity is increased from 50 kW/m2 to 5 MW/m 2.
Abstract: When using high‐power pulsed tunable dye lasers to measure plasma ion temperatures, it is important to attenuate the laser intensity. The temperature is found from the Doppler broadening of a spectral line. This may be obscured by saturation broadening, an instrumental effect encountered when too much laser intensity is used. Three useful experimental methods for determining the optimum pulsed laser intensity are found from a semiclassical atomic physics model. As an example, an Ar II transition pumped by a 1‐GHz bandwidth laser is examined. The fluorescence linewidth of room‐temperature ions broadens from 1.50 to 2.87 GHz when the homogeneous laser intensity is increased from 50 kW/m2 to 5 MW/m2.

44 citations

Book ChapterDOI
01 Oct 1997

44 citations

Journal ArticleDOI
TL;DR: The model proposed in this article is the first model that has successfully predicted speckle broadening in a self-mixing velocimetry sensor in a quantitative manner and was found that the beam spot size on the target and the target speed affect the resulting spectral broadening caused by Speckle.
Abstract: Self-mixing laser sensors require few components and can be used to measure velocity The self-mixing laser sensor consists of a laser emitting a beam focused onto a rough target that scatters the beam with some of the emission re-entering the laser cavity This ‘self-mixing’ causes measurable interferometric modulation of the laser output power that leads to a periodic Doppler signal spectrum with a peak at a frequency proportional to the velocity of the target Scattering of the laser emission from a rough surface also leads to a speckle effect that modulates the Doppler signal causing broadening of the signal spectrum adding uncertainty to the velocity measurement This article analyzes the speckle effect to provide an analytic equation to predict the spectral broadening of an acquired self-mixing signal and compares the predicted broadening to experimental results To the best of our knowledge, the model proposed in this article is the first model that has successfully predicted speckle broadening in a self-mixing velocimetry sensor in a quantitative manner It was found that the beam spot size on the target and the target speed affect the resulting spectral broadening caused by speckle It was also found that the broadening is only weakly dependent on target angle The experimental broadening was consistently greater than the theoretical speckle broadening due to other effects that also contribute to the total broadening

44 citations

Journal ArticleDOI
TL;DR: In this paper, a study of the Doppler broadening of resonances in the total cross section for interaction of slow neutrons with nuclei bound in crystals was made, and the shapes of the resonance lines were determined as a function of temperature by measuring the neutron transmission of thin and thick samples using the Argonne fast chopper.
Abstract: A study has been made of the Doppler broadening of resonances in the total cross section for interaction of slow neutrons with nuclei bound in crystals. The resonance at 6.71 ev in Os metal and the resonance at 6.65 ev in U metal were chosen as examples of moderate crystal binding, while the 6.65-ev resonance in U/sub 3/O/sub 6/, for which k THETA /sub o/ = 0.043 ev, was chosen as an example of strong binding. The shapes of the resonance lines were determined as a function of temperature by measuring the neutron transmission of thin and thick samples by means of the Argonne fast chopper. These shapes were compared with theoretical line shapes calculated by means of Lamb's theory of Doppler broadening as applied to the spectra of lattice frequencies implied by simple models of the crystal lattices. For moderate binding, a simple Einstein model which reproduces the observed specific-heat behavior of the crystal above 40 EK gives accurate resonance-line shapes at all temperatures. However, for U/sub 3/O/sub 6/ the line shapc implies a generalized Nernst-Lindemann model of the lattice with a frequency spectrum g( nu ) = 0.9 delta (h nu /sub 1/0.013 ev) + 0.1 delta (hmore » nu /sub 2/ -- 0.052 ev). The proportions of the high- and low- frequency components are quite different fiom the values resulting from specific- heat data. Possible interpretations of the U/sub 3/O/sub 8/ results in terms of simple lattice models are presented. (auth)« less

44 citations

Journal ArticleDOI
TL;DR: In this paper, high-pulse-energy supercontinuum radiation with a width exceeding 900 nm in the near-infrared spectral region has been generated in conventional single-mode fiber.
Abstract: High-pulse-energy supercontinuum radiation with a width exceeding 900 nm in the near-infrared spectral region has been generated in conventional single-mode fibre. The fibre was pumped at 1064 nm which is in the normal dispersion regime, resulting in predominantly red-shifted spectral broadening. Supercontinuum pulse energies exceeding 450 nJ were obtained. The use of conventional fibre allows for inexpensive generation of near-infrared supercontinuum radiation, featuring high pulse energies and good spatial beam quality. This supercontinuum radiation was used to acquire high-resolution (15 pm) broadband absorption spectra of H2O, C2H2 and C2H4 in the near-infrared spectral region (1340–1700 nm), using an optical spectrum analyser for detection. H2O spectra were also recorded at high repetition rates, by dispersing the supercontinuum pulses and detecting the transmitted signal in the time domain. A spectral resolution of 38 pm was obtained employing the dispersed supercontinuum pulses, which is comparable to the H2O line widths at ambient conditions.

44 citations


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