Doppler broadening

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Doppler broadening

(dop -ler) Broadening of spectral lines due to the random motion of emitting or absorbing atoms. As a result of the Doppler effect, atoms moving away from the observer show lines with a slight shift to longer wavelengths; atoms moving toward the observer show a slight shift to shorter wavelengths. The overall effect is that the line is broader than the natural width (determined by quantum mechanical uncertainty).

The motion of the atoms may be due to thermal motion, in which case the effect is larger for lighter atoms. Turbulence of stellar material, rapid rotation of a star, or an expanding stellar atmosphere can also produce Doppler broadening. See also line broadening.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

Doppler broadening

[′däp·lər ‚brȯd·ən·iŋ]
(spectroscopy)
Frequency spreading that occurs in single-frequency radiation when the radiating atoms, molecules, or nuclei do not all have the same velocity and may each give rise to a different Doppler shift.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
To show the benefits more clearly, Figure 10(c) shows the Doppler profile with the 2nd beam bin and the 141st range bin, which have the same direction and range with the injected target.
From the comparison results in range-Doppler spectrum and Doppler profile, the proposed algorithm can absolutely restrain radio and clutter while introducing no false target outside the injected target position.
The Doppler profile, on the other hand, is a TF-dependent function that depends only on the channel's angular statistics.
In the remainder of this section, we present some graphical examples of the 4D TF-CF [R.sub.H](t, f; [DELTA]t, [DELTA]f) in (45) and the corresponding time-varying delay profile [P.sub.H](t; [tau]) and TF-dependent Doppler profile [D.sub.H](t, f; v).
Time-Frequency Dependent Doppler Profile. Finally, Figure 6 shows a 3D graph and a contour plot of the TF-varying Doppler profile [D.sub.H](t, f; v) evaluated at t = 0.8[T.sub.0].
Caption: Figure 6: Absolute value of the TF-varying Doppler profile [D.sub.H](t, f; v) for t = 0.8[T.sub.0] and [T.sub.0] = 320 ms.
Caption: Figure 7: Contour plot of the absolute value of the TF-varying Doppler profile [D.sub.H](t, f; v) for t = 0.8[T.sub.0], [T.sub.0] = 320 ms, and an extended observation window in the frequency domain.
In 24 chapters, anesthesiologists and cardiologists from the US explain the principles of ultrasound and Doppler ultrasound; transducers and instrumentation; equipment, infection control, and safety; quantitative M-mode and 2D echocardiography; quantitative Doppler; Doppler profiles and assessment of diastolic function; cardiac, pericardium and extra-cardiac, and cardiac valve anatomy and pathology; intra-cardiac masses and devices; left ventricular and segmental left ventricular systolic function; the 17 segment model; assessment of perioperative events and problems; congenital heart disease; artifacts and pitfalls; related diagnostic modalities; the structured TEE examination; and sonographic formulas.
The fact that the DGR is superior to the STFT is confirmed from Figure 8, which shows the time-frequency plots and the Doppler profiles of the time-domain signal at the selected 35th range cell.
The program can also be used to make these measurements on one-dimensional range or Doppler profiles.
The true Doppler profiles at three ranges are shown in Figure 4.