Topic
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 authors consider the observability of such fluid motions via the distortions they induce in the CMB via the kinematic SZ effect, as well as via Doppler broadening and shifting of metal lines in the X-ray spectrum.
Abstract: Coolingflows, cluster mergers, and the motions of galaxies through cluster gas with supersonic and sonic velocities must lead to large scale motions of the intracluster medium (ICM). A high-resolution numerical simulation of X-ray cluster formation by Norman and Bryan (1999) predicts cluster-wide turbulence with νturb ≈300–600 km s∓1 and eddy scales l
outer ≈100–500 kpc, the larger numbers being characteristic of turbulence near the virial radius, while the smaller numbers pertain to the core. The simulation also predicts the existence of ordered bulk flows in the core with v≈400 km s−1 on scales of several hundred kpc. In this paper, we consider the observability of such fluid motions via the distortions they induce in the CMB via the kinematic SZ effect, as well as via Doppler broadening and shifting of metal lines in the X-ray spectrum. We estimate |ΔT/T|kinematic
125 citations
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TL;DR: In this article, the authors measured the diffuse reflection spectrum of solid samples such as explosives (TNT, RDX, PETN), fertilizers (ammonium nitrate, urea), and paints (automotive and military grade) at a stand-off distance of 5m using a mid-infrared supercontinuum light source with 3.9 W average output power.
Abstract: We measure the diffuse reflection spectrum of solid samples such as explosives (TNT, RDX, PETN), fertilizers (ammonium nitrate, urea), and paints (automotive and military grade) at a stand-off distance of 5 m using a mid-infrared supercontinuum light source with 3.9 W average output power. The output spectrum extends from 750–4300 nm, and it is generated by nonlinear spectral broadening in a 9 m long fluoride fiber pumped by high peak power pulses from a dual-stage erbium-ytterbium fiber amplifier operating at 1543 nm. The samples are distinguished using unique spectral signatures that are attributed to the molecular vibrations of the constituents. Signal-to-noise ratio (SNR) calculations demonstrate the feasibility of increasing the stand-off distance from 5 to ∼150 m, with a corresponding drop in SNR from 28 to 10 dB.
124 citations
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TL;DR: A new model of pump noise in supercontinuum and rogue wave generation is presented and it is found that for four-wave mixing (FWM) a narrow spectral line width initially leads to a build-up of FWM from quantum noise, whereas a broad spectral linewidth initially leading to a gradual broadening of the pump spectrum.
Abstract: A new model of pump noise in supercontinuum and rogue wave generation is presented. Simulations are compared with experiments and show that the new model provides significantly better agreement than the currently ubiquitously used one-photon-per-mode model. The new model also allows for a study of the influence of the pump spectral line width on the spectral broadening mechanisms. Specifically, it is found that for four-wave mixing (FWM) a narrow spectral line width (≲ 0.1 nm) initially leads to a build-up of FWM from quantum noise, whereas a broad spectral line width (≳ 1 nm) initially leads to a gradual broadening of the pump spectrum. Since the new model provides better agreement with experiments and is still simple to implement, it is particularly important that it is used for future studies of the statistical properties of nonlinear spectral broadening, such as the formation of rogue waves.
123 citations
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TL;DR: In this article, the collision narrowing effect and collision broadening and shift of several vibrational Raman lines in hydrogen and deuterium gas were investigated and the results fall between two simple extreme models for the velocity change in a single collision.
123 citations
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TL;DR: In this paper, a Doppler broadening spectrometer was used to measure the low and high-momentum annihilation fractions, S and W, respectively, as a function of positron energy in polycrystalline tungsten samples implanted at different fluences from 10 14 to 5 × 10 16 ǫ cm −2.
123 citations