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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 paper, the authors show that the Doppler broadening, which arises in a fast-beam light source because of the high speed of the emitters and the nonzero acceptance angle of the spectrometer, can often be practically eliminated by proper adjustment of the Spectrometer.
Abstract: We show that the Doppler broadening, which arises in a fast‐beam light source because of the high speed of the emitters and the nonzero acceptance angle of the spectrometer, can often be practically eliminated by proper adjustment of the spectrometer.
68 citations
TL;DR: In this article, the authors show that initially narrow band upgoing signals from ground-based VLF transmitters undergo a significant spectral broadening as they propagate through the ionosphere and protonosphere, up to altitudes in the 600-3800 km range.
Abstract: ISIS 1 and 2 and ISEE 1 VLF/ELF electric field wave data indicate the existence of a novel phenomenon, in which initially narrow band upgoing signals from ground-based VLF transmitters undergo a significant spectral broadening as they propagate through the ionosphere and protonosphere, up to altitudes in the 600-3800 km range. For transmitter signals in the 10-20 kHz range, the spectral broadening can be as high as 10 percent of the input signal's nominal frequency. In many cases, the bandwidth of the spectrally broadened signals is a strong function of the electric dipole antenna orientation with respect to the local direction of the earth's magnetic field. The unusual dispersion in the components of the spectrally broadened pulses suggests that the spectral broadening may be due to a Doppler shift effect in which the initial signals scatter from irregularities in the F region and couple into quasi-electrostatic modes of short wave length.
68 citations
TL;DR: It is shown that the SBS spectral width and gain depend on the numerical aperture for both single-mode and multimode fibers, the functional dependencies of which are in good agreement with the model description of the phenomenon.
Abstract: We provide direct experimental evidence of waveguide-induced inhomogeneous spectral broadening of stimulated Brillouin scattering (SBS) in optical fiber. It is shown that the SBS spectral width and gain depend on the numerical aperture for both single-mode and multimode fibers, the functional dependencies of which are in good agreement with our model description of the phenomenon.
68 citations
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TL;DR: In this article, the authors focus on the recent results obtained with the help of synthetic spectra for supernova flux and polarization spectra, which can be inferred directly from the observed line profiles and fluxes, but because of the Doppler broadening and severe line blending, interpretation often involves the use of synthetic spectrum.
Abstract: Supernova flux and polarization spectra bring vital information on the geometry, physical conditions, and composition structure of the ejected matter. For some supernovae the circumstellar matter is also probed by the observed spectra. Some of this information can be inferred directly from the observed line profiles and fluxes, but because of the Doppler broadening and severe line blending, interpretation often involves the use of synthetic spectra. The emphasis in this Chapter is on recent results obtained with the help of synthetic spectra.
68 citations
TL;DR: In this paper, an experiment has been performed to measure the quadratic Doppler shift, ∼(1−υ2/c2)−12, predicted by the special theory of relativity.
Abstract: An experiment has been performed to measure the quadratic Doppler shift, ∼(1−υ2/c2)−12, predicted by the special theory of relativity. A moving beam of radiating hydrogen atoms with velocities ranging up to 2.8 × 108 cm/sec has been viewed from the incoming and outgoing directions simultaneously. Averaging wavelength measurements of a particular spectral line for the two observations gives a measurement of the quadratic shift. The number (12) in the theoretically predicted exponent can be compared to the experimental results. The latter gives the value of this exponent to be 0.498 ± 0.025. The predominant factor leading to the experimental uncertainty is the width of the spectral lines involved in the measurement.
68 citations