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Topic: Doppler broadening

	Broadening of Spectral Lines (Site not responding. Last check: 2007-09-07)
		One source of broadening is the "natural line width" which arises from the uncertainty in energy of the states involved in the transition.
		This source of broadening is important in nuclear spectra, such as Mossbauer spectra, but is rarely significant in atomic spectroscopy.
		For atomic spectra in the visible and uv, the limit on resolution is often set by Doppler broadening.
	hyperphysics.phy-astr.gsu.edu /hbase/atomic/broaden.html (293 words)

	Doppler broadening - Wikipedia, the free encyclopedia
		In atomic physics, Doppler broadening is the broadening of spectral lines due to the Doppler effect in which the thermal movement of atoms or molecules shifts the apparent frequency of each emitter.
		The broadening is dependent only on the wavelength of the line, the mass of the emitting particle and the temperature, and can therefore be a very useful method for measuring the temperature of an emitting gas.
		In Astronomy, Doppler broadening is one of the explanations for the broadening of spectral lines, and as such gives an indication for the relative temperatures of observed material.
	en.wikipedia.org /wiki/Doppler_broadening (691 words)

	NIST: Atomic Spectros. - Spectral Line Shapes, etc.
		Observed spectral lines are always broadened, partly due to the finite resolution of the spectrometer and partly due to intrinsic physical causes.
		Doppler broadening is due to the thermal motion of the emitting atoms or ions.
		Resonance broadening (self-broadening) occurs only between identical species and is confined to lines with the upper or lower level having an electric dipole transition (resonance line) to the ground state.
	physics.nist.gov /Pubs/AtSpec/node20.html (455 words)

	Doppler Correction (Site not responding. Last check: 2007-09-07)
		Doppler broadening is the spread in measured energy caused when gamma rays from moving nuclei are observed using a stationary detector whose opening angle is large enough to accept varying angles of incidence.
		Doppler broadening can be corrected, but to do so we must know the angle between the origin of the gamma rays and the detection point.
		The effectiveness of the Doppler correction is proportional to the precision of the hit position determination but is limited by delta-v and delta-theta.
	nnsa.dl.ac.uk /GRT/Doppler.htm (269 words)

	The Lamb Shift by Saturation Spectroscopy (Site not responding. Last check: 2007-09-07)
		In a low pressure gas, the main source of broadening is Doppler broadening from the thermal motion of the atoms or molecules of the gas.
		Tunable dye lasers are used to excellent advantage in "Doppler-free saturation spectroscopy" to minimize the effects of the Doppler broadening.
		The only hydrogen atoms which are in resonance with both of the beams are those which have no component of velocity in the direction of the beams, and therefore absorb at the frequency associated with the rest frame of the atom.
	hyperphysics.phy-astr.gsu.edu /hbase/quantum/lamb2.html (405 words)

	Spectral line - {{ᏏᏖᎾᎺ}} (Site not responding. Last check: 2007-09-07)
		ᎪᎯ broadening ᎢᏳᎵᏍᏙᏗ ᎨᏒᎢ ᏄᏍᏛ ᎧᏃᎮᎸ ᎾᎥᎢ Doppler ᏌᏆᎦᏘ ᎠᎴ ᎾᎿᎢ ᎨᏒᎢ Ꮭ ᎤᎾᎵᎪᏅᎯ ᏗᏓᏁᏟᏴᏍᏗ.
		ᎤᏬᎩᎸ broadening: ᎤᎪᏗ reabsorption ᏗᏓᏲᎯᏍᏗ ᎠᏍᏓᏅᏅ photons, ᎢᏳᎵᏍᏙᏗ ᎤᎾᏅᏛ ᏥᏄᏍᏗ ᎤᏬᎩᎸ, ᎢᏳᏓᎵᎭ ᏂᏕᎬᏂᏏᏍᎬ ᎠᏍᏓᏅᏅ broadening.
		ᎯᎠ ᎠᏍᏓᏅᏅ ᎨᏒᎢ broadened ᎣᏂ ᏧᏩᎫᏛ photons ᎾᎾᎢ ᎯᎠ ᎠᏍᏓᏅᏅ ᎪᏯᏛ ᎤᎭ ᎠᏂᎦᏲᎵ reabsorption ᎤᏝᏅᏓᏕᎲ ᎬᎾᏬᏍᎬ photons ᎾᎾᎢ ᎯᎠ ᎠᏍᏓᏅᏅ ᎠᏰᎵ.
	www.wikigadugi.org /wiki/Spectral_line (986 words)

	Lecture 23
		Natural Broadening -- this is inversely proportional to the time that the atom remains in the excited state, according to Heisenberg's Uncertainty Principle.
		Doppler Broadening -- In thermal equilibrium, atoms in a gas have a distribution of speeds that follows the Maxwell-Boltzmann distribution.
		For Doppler Broadening, the line shape is approximately Gaussian, in reflection of its dependence on the Maxwell velocity distribution.
	www.astrobio.nau.edu /~koerner/ast301/lecture/lecture23/lec23.html (635 words)

	U238 doppler broadening (Edward C. Wood) (Site not responding. Last check: 2007-09-07)
		It arises from broadening of resonances in the capture cross-section of U-238 due to thermal motion of the nuclei.
		A neutron with, relative to the mean positions, a velocity that is close to a resonance can be right on it relative to some moving nucleus.
		Increasing temperature, which increases thermal agitation velocities of nuclei, increases the velocity difference that is described as 'close', thus broadens resonances and reduces the fraction of neutrons that escape resonance capture.
	yarchive.net /nuke/238_doppler_broadening.html (551 words)

	FM Saturation Spectroscopy
		Since the thermal velocities are non-relativistic, the Doppler shift in the angular frequency of the light absorbed by atoms traveling towards or away from a stationary source is given by the simple form
		Power broadening occurs because of the shortening of the lifetime of the excited states due to stimulated emission.
		Saturation spectroscopy eliminates Doppler broadening by directing the saturation beam and the probe beam through the gas in opposite directions.
	electron9.phys.utk.edu /optics507/modules/m10/saturation.htm (1681 words)

	[No title]
		In addition, to observe rotational Doppler broadening the atom must gain or loose a unit of angular momentum during the absorption.
		However, the observation of rotational Doppler broadening requires light with orbital angular momentum, called twisted light because the electric field traces out a crazy corkscrew (see the movie*).
		To observe the rotational Doppler broadening, researchers illuminated a cell of Rubidium atoms with two twisted light beams.
	arstechnica.com /journals/science.ars/2006/10/26/5762 (676 words)

	Doppler-Free Saturated Absorption Spectroscopy
		This Doppler broadening of spectral absorption lines was seen clearly for the 6678 Å He absorption line of Expt.
		The effects of Doppler broadening can be overcome in a pump-probe saturated absorption measurement scheme such as the one shown in Fig.
		The lineshape of the probe signal detected by the lock-in detector is therefore determined by the natural linewidth of the atomic transition and not by the effects of Doppler broadening.
	cat.middlebury.edu /~PHManual/dopfree.html (3224 words)

	[No title]
		` ` ` 30 Christian Baude tumanz 2/18/98 6:01 PM b b c ` By "inordinately large" large Doppler broadening ` ` The curve of growth is a log-log plot which shows the relationship between W and Na (the width of the spectral line and the number of absorbing ions per unit area).
		The width grows in a certain relationship to N (which is used to find the abundance of elements), and so by working from the thickness of the absorption lines, astronomers can deduce the abundance of different elements.
		Thus if the Doppler broadening of a spectral line is much larger than expected, the presence of turbulence can be deduced.
	www4.hmc.edu:8001 /Physics/quizzes/Astro62/1998/astr08.txt (1392 words)

	Encyclopedia of Laser Physics and Technology - Doppler broadening, Doppler effect, linewidth
		Doppler broadening is the broadening of the linewidth of atomic transitions caused by the random movements of atoms.
		For this formula it is assumed that the Doppler broadening is much larger than the natural linewidth, which is typically the case e.g.
		Doppler broadening is the dominant line broadening mechanism in gas lasers.
	www.rp-photonics.com /doppler_broadening.html (266 words)

	Doppler - Wikipedia, the free encyclopedia
		the Doppler effect, where the frequency of a wave changes with the relative velocity between the source and the observer
		Doppler broadening - Atoms in thermal motion emit doppler-shifted radiation.
		Doppler, the mascot of the WNBA's Seattle Storm.
	en.wikipedia.org /wiki/Doppler (131 words)

	[No title]
		The temperature is found from the Doppler broadening of a spectral line.
		One type of instrumental broadening, encountered with the use of high intensity pulsed lasers, is the result of power saturation.
		This broadening can be understood by examining how these processes change the population densities of three states of an ion, denoted 0, 1, and 2.
	dusty.physics.uiowa.edu /~goree/papers/LIF_power_sat.html (2760 words)

	Modeling Information (Site not responding. Last check: 2007-09-07)
		It is an example of a homogeneous broadening mechanism (since all the atoms contribute in the same way).
		Doppler (or thermal) broadening is an example of inhomogeneous broadening (since each atom moves with different relative velocities and contribute in a different way).
		Doppler effect for sound waves is familiar and can be seen when a whistling train passes by the observer.
	www.engr.colostate.edu /me/ipr/CRDS/Modeling.htm (1297 words)

	Moderator (Site not responding. Last check: 2007-09-07)
		The phenomenon of the doppler effect is caused by an apparent broadening of the resonances due to thermal motion of nuclei as illustrated in Figure 3.
		Raising the temperature causes the nuclei to vibrate more rapidly within their lattice structures, effectively broadening the energy range of neutrons that may be resonantly absorbed in the fuel.
		The Doppler broadening of resonance peaks occurs because the nuclei may be moving either toward or away from the neutron at the time of interaction.
	www.tpub.com /doenuclearphys/nuclearphysics64.htm (1137 words)

	Notes part 4
		(i) Natural broadening -- which is a quantum mechanical limit due to the natural lifetime of the level(s) producing the transition.
		(ii) Doppler broadening -- due to thermal motion of emitting atoms.
		Gaussian profile, Doppler broadened when comprised of an ensemble of different groups of atoms each with a different lineshape function
	www.sun.rhbnc.ac.uk /~uhap045/331/notes4/notes4.html (486 words)

	SPECTRUM ANALYSIS
		This mechanism is the principal broadening agent for weaker lines but not for hydrogen, though the effect is apparent right at the line wavelength.
		For hydrogen and certain lines of helium the broadening of H by other H atoms (self-broadening) is particularly effective, an interaction often called the linear Stark broadening.
		In stellar spectra the lines usually appear broadened but the light is also polarized and the degree of polarization is related to the splitting.
	www.physics.uq.edu.au /people/ross/phys2080/spec/photo.htm (1430 words)

	Ge Clover Detectors - CANBERRA, An AREVA Group Company
		In the CLOVER detector assembly, the crystals are hold only by the rear side thus reducing the quantity of material surrounding the crystal and improving peak to background ratio.
		The reduction of the crystal opening angle permits a Doppler broadening reduction.
		Accurate location of the interaction points allows not only reduction of Doppler broadening, but also gamma ray tracking in the detector.
	www.canberra.com /Products/1112.asp (606 words)

	Introduction to Positron Research
		Doppler Broadening allows us to measure the energy of the gamma rays using a high-purity Germanium detector (HPGe).
		The Doppler effect describes how the frequency of a wave emitted from a moving source changes depending on the relative motion between the source and the observer.
		This Doppler broadening winds up being very important, because we can infer useful information from the width of the peak using statistical analysis software.
	www.stolaf.edu /academics/positron/intro.htm (1207 words)

	Collisional Broadening Theory
		The broadening of spectral lines by collisions with atomic hydrogen is important for abundance determinations in cool stars, since it is a very important broadening mechanism in strong lines.
		The collisional broadening theory of Anstee and O'Mara (MNRAS 1991, 253, p549) was used to produce tables of broadening cross sections for s-p and p-s transitions as a function of effective principal quantum number (see Anstee and O'Mara MNRAS 1995, 859).
		Barklem, B. O'Mara, The broadening of p-d and d-p transitions by collisions with neutral hydrogen atoms.
	www.physics.uq.edu.au /people/barklem/research.html (552 words)

	IAEA1416: SIGACE, Code for Doppler broadening of ACE-formatted files
		The low temperature ACE file is first converted to ENDF formatted file using the ACELST code and then Doppler broadened, essentially limited to the data in the resolved resonance region, to any desired higher temperature using SIGMA1.
		The Doppler Broadened ACE file can then again be converted to ENDF file and graphically plotted using EVALPLOT and compared with other ENDF file using COMPLOT routines of the PREPRO code system for validation purposes.
		The original DOS/WINDOWS version of the code system allows to plot for comparison the source ACE file with the output Doppler broadened file by means of the COMPLOT code, whose DOS executable is included in the package; in the current version this feature has been maintained for DOS/WINDOWS, but it is not available for linux.
	www.nea.fr /abs/html/iaea1416.html (382 words)

	The Doppler Effect
		The Doppler effect is observed for ALL wave motions (from g to radio), where there is relative motion.
		Details of the Doppler effect may be found in any A-level (or equivalent) textbook, including a derivation of the general formulae for the Doppler effect:
		The atoms/molecules/ions that are emitting light within a star are not at rest: they are moving around in random directions, at high speed - the speed is determined by the temperature of the hot gas.
	www.egglescliffe.org.uk /physics/astronomy/doppler/doppler.html (1085 words)

	Factors affecting Lineshape of emission lines (Site not responding. Last check: 2007-09-07)
		At the origine is the natural line shape, which can be altered by the Doppler effect and pressure broadening.
		Other broadening mechanisms altering the physical lineshape are fine and hyperfinestructures, electircal and magnetic fields.
		As the natural line shape of one atom is Lorentzian and the population of the moving atoms generate a Gaussian lineshape the resulting physical lineshape is a convolution of the Lorentzian and Gaussian line shape.
	www.thespectroscopynet.com /Theory/Lineshape.htm (568 words)

	ISSAS Spectroscopy Trivia
		, 1842, Christian Doppler delivered a lecture to the Royal Bohemian Scientific Society entitled ‘concerning the coloured light of double stars and some other heavenly bodies’ in which he stated that light waves change frequency of oscillation, hence color, when a light source or observer is in motion relative to the other.
		In studies similar to Doppler’s original application, the Doppler effect has been used to calculate the size of the universe.
		In spectroscopy, Doppler broadening of atomic emission lines is a convenient method for determining gas temperatures.
	www.indiana.edu /~issas/trivia/may00_trivia.html (309 words)

	Laser spectroscopy of nanometric gas cells
		The Doppler effect plays an important role in the optical spectra of atomic or molecular species, from which one can analyse their characteristic emission frequencies.
		In particular, if the atom absorbs simultaneously two photons of the same frequency, each travelling in counter-propagating directions, the Doppler shifts respectively associated with either absorption are exactly opposite, and their sum cancels, leading to a zero Doppler shift, whatever the atomic velocity may be [3].
		When the incident light is normal to the surface, the Doppler effect cancels for those atoms moving at grazing incidence: the light absorption becomes free of Doppler broadening, as has been demonstrated in thin cells of Cs gas at the D2 resonance line,
	www.europhysicsnews.com /full/26/article2/article2.html (2578 words)

	Segmented Germanium Detectors
		Segmenting germanium detectors reduces the Doppler broadening and the Isolated hit probability.
		Further position information can be obtained by carrying out a pulse shape analysis in conjunction with the crystal segmentation This is based on the fact that interactions occurring in different parts of the crystal will produce preamplifier pulses with different shapes.
		The extra position information obtained enables the interaction angle to be deduced more precisely and hence the resolution of the crystal lost due to Doppler broadening, can be recovered.
	ns.ph.liv.ac.uk /posters/sls/poster.html (436 words)

	[No title]
		The combination of both Doppler and collisional processes leads to a complex change in the equivalent width of a spectral line as the optical depth increases.
		eventually, the wings due to collisional broadening overwhelm the Doppler wings, even though the collisional term is much smaller near the line center.
		A plot of the equivalent width W as a function of the number of absorbing atoms N is called the curve of growth.
	spiff.rit.edu /classes/phys440/lectures/curve/curve.html (1177 words)

	Exercise 4: Resonance Doppler Broadening (Site not responding. Last check: 2007-09-07)
		You can see how the Doppler broadening changed the sharp 0K resonance into the broader resonance appropriate to 10000K.
		Note the the grid points are very close together near the resonance energy for the 0K curve, and more widly spaced out on the shoulders of the curve.
		The broadened curve, on the other hand, has widely spaced points near the resonance energy, and the closely spaced points appear out on the steep descents at the "Doppler width."
	t2.lanl.gov /njoy/exer04.html (239 words)

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