
	Where results make sense

Topic: Hyperfine transition

Related Topics

Atomic clock

Caesium

In the News (Tue 29 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Hyperfine structure - Wikipedia, the free encyclopedia
		In atomic physics, hyperfine structure is a small perturbation in the energy levels (or spectra) of atoms or molecules due to the magnetic dipole-dipole interaction, arising from the interaction of the nuclear magnetic dipole with the magnetic field of the electron.
		Carl Sagan and Frank Drake considered the hyperfine transition of hydrogen to be a sufficiently universal phenomenon so as to be used as a base unit of time and length on the Pioneer plaque and later Voyager Golden Record.
		Typically, the hyperfine structure transition frequency of a particular isotope of caesium or rubidium atoms is used as a basis for these clocks.
	en.wikipedia.org /wiki/Hyperfine_structure (735 words)

	Fine tuning of atomic frequency standards - Patent 4740761
		The number of atomic state transitions in the atomic frequency resonator 14 is maximum when the frequency of the phase modulated transition inducing signal 16 is equal to the hyperfine transition resonance center frequency of the resonator 14.
		According to the present invention, the hyperfine transition resonance center frequency of the atomic resonator 14 remains fixed, and a DC bias offset signal 38 is applied to the input of the summing integrator 34 in the frequency-lock loop.
		Since the hyperfine transition resonance center frequency f.sub.r and the new synthesized center frequency f.sub.c no longer coincide, an error signal 32 is produced which is proportionately related to the difference between f.sub.r and f.sub.c.
	www.freepatentsonline.com /4740761.html (2812 words)

	How a cesium beam atomic clock works
		The frequency involved is determined by the energy of the incident microwave photons when they excite hyperfine transitions in the atom.
		Transitions at many different energies are possible; those discussed here occur at very low energy and refer to changes in the magnetic interaction between electron and nuclear spins (hyperfine interaction) in the atomic ground state.
		This locking of the microwave frequency to the atomic transition frequency is the heart of the extreme stability of the atomic clock.
	www.aero.org /publications/crosslink/winter2000/02_sidebar1.html (679 words)

	GPS: The Role of Atomic C... - Rabi's Clock
		When an atom undergoes a transition from one such "energy state" to a lower one--it emits an electromagnetic wave of a discrete characteristic frequency, known as the resonant frequency.
		In particular, he proposed using the frequencies of what are known as "hyperfine transitions" of the atoms--transitions between two states of slightly different energy corresponding to different magnetic interactions between the nucleus of an atom and its electrons.
		The closer the oscillation frequency of that field to the frequency of the hyperfine transition of the atom, the more atoms absorb energy from the field and thereby undergo a transition from the original hyperfine state to another one.
	www.beyonddiscovery.org /content/view.page.asp?I=466 (476 words)

	Integrated microwave cavity resonator and magnetic shield for an atomic frequency standard - Patent 4661782
		A microwave cavity resonator for an atomic frequency standard comprising a cavity resonator defined by high magnetic permeability and containing therein a supply of atoms capable of undergoing a hyperfine transition within a microwave region of the spectrum, and means within said resonator for inducing the hyperfine transitions.
		By properly slaving the quartz crystal oscillator to the frequency of the atomic transition, the tendency of the quartz crystal to exhibit drifting due to aging and other inherent as well as environmental effects is markedly suppressed.
		As the atoms drop into the lower ground state hyperfine level from the upper ground state hyperfine levels, a correspondingly smaller amount of light reaches the photodetector 16 since light is being actively absorbed by Rb87.
	www.freepatentsonline.com /4661782.html (3579 words)

	Hyperfine Structure
		Consider first the case l=0, since the hyperfine splitting of the hydrogen atom ground state is of the most interest.
		The transition is exceedingly slow, but the huge amounts of interstellar hydrogen make it readily observable.
		It is too slow to be seen in a terrestrial laboratory by spontaneous emission, but the frequency can be measured to very high accuracy by using stimulated emission, and this frequency is in fact one of the best-known numbers in all of physics.
	www.pha.jhu.edu /~rt19/hydro/node9.html (798 words)

	HP 5062C
		This transition is well suited to use in a frequency standard because it is very nearly independent of the external magnetic field, whereas for other transitions, there is a linear dependence upon field.
		This separation of the energy dependent transitions, which is a known and sensitive function of the C-Field, is used to set the C-Field and to align the 5062C.
		It is convenient to produce the frequencies used to excite the field dependent transitions by modulating the output of the 5062C's harmonic generator such that sidebands lie at the desired frequencies.
	www.leapsecond.com /museum/hp5062c/theory.htm (2343 words)

	Rb Spectroscopy
		By feeding this signal into a lock-in amplifier as feedback, an error signal is established that repeatedly forces the laser back onto the peak of the hyperfine transition as the laser output naturally drifts in one direction or the other, away from the peak.
		The Rb “transition” may be quickly confirmed and monitored through the use of a CCD camera focused onto the atomic vapor cell probed with laser beam.
		That is, if a portion of the transition width is excited by a particular mode, the laser current may be changed to quickly tune the output by shifting the lasing mode by a small enough increment until the mode engulfs the transition width.
	laser.physics.sunysb.edu /~bazmoun/RbSpectroscopy (11458 words)

	10.1.2.5
		When the frequency of this oscillating field exactly matches a natural atomic resonance ground-state hyperfine transition frequency of Cs (~9.192,631,770 GHz), the spin energy state can switch polarity, allowing "flipped" atoms to focus, rather than defocus, at the second fixed magnet.
		However, many problems must be overcome including interactions involving spontaneous decay, measurement-induced transitions, phase changes due to gas molecule collisions, spatial confinement effects, the use of symmetries and cancellation of couplings.
		J. Soreff [personal communication, 1998] suggests consideration of an oscillator structure in which a phosphorus atom is covalently bound to a tetrahedral support of carbyne rods extending to the ends of an evacuated chamber.
	www.nanomedicine.com /NMI/10.1.2.5.htm (504 words)

	IEEE UFFC Frequency Control Home
		Ramsey discovered that the application of the transition stimulating oscillating field could be limited, as with the interferometer, to the two ends of the transition region, and indeed with a significant gain in resolution.
		As the intrinsic width of these hyperfine transitions is negligible, the effective width of the resonance is simply the resolution of the atomic beam apparatus.
		Though this technique of frequency modulation of the transition field was to be essential in the next, industrial stage of development, in the summer of 1954 it added further degrees of complication to an apparatus whose operation was at all times precarious [74].
	www.ieee-uffc.org /fcmain.asp?page=atomichron (14520 words)

	"Atomic" Clock
		The energies of the hyperfine interaction occur in the radio and microwave region.
		Specifically, a second was defined as the duration of 9,192,631,770 cycles of microwave light absorbed or emitted by the hyperfine transition of cesium-133 atoms in their ground state, undisturbed by external fields.
		This frequency, the atoms' natural hyperfine transition frequency, is counted to determine the length of a second
	www.4physics.com /phy_demo/at_clock/at_clock.htm (1626 words)

	Carl Sagan Â«Pioneer PlaqueÂ» 1972. \| Î¦rbitÂ° sÏaceÏlace :: art in the age Ã¸f Î¦rbitizatiÃ¸n (Site not responding. Last check: 2007-10-13)
		At the top left of the plate is a schematic representation of the hyperfine transition of hydrogen, which is the most abundant element in the universe.
		This spin-flip transition of a hydrogen atom from electron state spin up to electron state spin down can specify a unit of length (wavelength, 21 cm) as well as a unit of time (frequency, 1420 MHz).
		In units of the wavelength of the hyperfine transition of hydrogen this means 8 Ã— 21 cm = 168 cm.
	mobile.orbit.zkm.de.cob-web.org:8888 /?q=node/256 (624 words)

	Physics Today March 2001
		Each hyperfine level is composed of several magnetic substates whose degeneracies are removed in the presence of an external magnetic field.
		The transition frequency between these two states (corrected to zero field) is used as the best approximation of the second because it is the least sensitive to the applied magnetic field.
		There, the absorption of a single clock photon is indicated by the presence or absence of scattered light on a strongly allowed transition (usually the laser-cooling transition) that shares a common level with the clock transition, as shown in figure 3.
	physicstoday.org /pt/vol-54/iss-3/p37.html (3973 words)

	Optical Frequency Standards and Metrology at NPL: Spectroscopy of the strontium-87 ion
		However, the spectroscopy of this isotope is complicated by the hyperfine structure arising from the large nuclear spin, which is shown in the term scheme on the right.
		This has allowed the determination of the hyperfine transition with the smallest quadratic Zeeman shift.
		Furthermore, although the use of a transition which is insensitive to magnetic fields to first order would simplify the algorithm used to stabilize the probe laser to the clock transition frequency compared to the even isotope, the flbody Zeeman shift of the clock transition frequency is much more significant for the odd isotope.
	www.npl.co.uk /optical_frequency_standards/npl_research/ion_trapping/strontium_87.html (446 words)

	E to G
		The so-called electrode potential of an electrode is defined as the electromotive force (emf) of a cell in which the electrode on the left is a standard hydrogen electrode and the electrode on the right is the electrode in question.
		When additional hyperfine splittings due to other nuclearspecies are resolved ("superhyperfine"), the nomenclature should include the designation of the nucleus, and the isotopic number.
		The frequency-domain spectrum corresponds to hyperfine transition frequencies.
	www.chem.qmul.ac.uk /iupac/bioinorg/EG.html (1793 words)

	PHYSICS LAB: TECH. ACTIVITIES 1997 Div 847
		The two clock transitions are the hyperfine transition at 40.5 GHz and the electric-quadrupole transition at 282 nm.
		The frequency of this transition has been measured at PTB and is now recognized as providing the highest-accuracy reference for realization of the meter.
		The cold atoms are then probed on the narrow "clock" transition at 657 nm with a diode laser using the method of time-domain, optical Ramsey interrogation.
	physics.nist.gov /TechAct.97/Div847/div847h.html (5287 words)

	[No title]
		Significant improvement of atomic clocks is now sought in the use of a higher transition frequency of the oscillator.
		This one-photon transition has a weak amplitude due to hyperfine coupling with the nuclear spin.
		The transition frequency in optical clocks can be shifted by Doppler and recoil shifts after absorption of a photon.
	astro.temple.edu /~skotoch/Research/clocks.html (400 words)

	Walter R. Johnson
		Applications of MBPT to give accurate energies, transition rates, and hyperfine constants for low-lying levels of ions in various isoelectronic sequences.
		CI calculations of energies, transition probabilities, hyperfine quenching, polarizabilities, and two-photon transitions in heliumlike ions.
		Third-order negative-energy contributions to transition amplitudes in heliumlike ions.
	www.nd.edu /~johnson (1042 words)

	The hyperfine structure of the hydrogen molecular ion
		The hyperfine structure of the hydrogen molecular ion*
		Theoretical investigations of the hyperfine structure of the hydrogen molecu-
		measurements of the hyperfine structure of the deuterium molecular ion (or
	www.cfa.harvard.edu /~babb/Babb-APCTP.html (1857 words)

	The Why Files \| 2. Time on the atomic scale
		In an atomic clock, the oscillations occur in an electromagnetic field that causes transitions between the two possible quantum-mechanical conditions of an atom.
		Atoms can have one of two "hyperfine states," and this is the basis of the atomic clock.
		The idea of building a clock around hyperfine states was proposed by physicist Isador Rabi in 1945.
	whyfiles.org /078time/index.php?g=2.txt (1522 words)

	4) METRIC USED (The BIPM has been transferred in Belgium at this address !).
		The absolute second is equal to 9,192,631,770 periods of the hyperfine transition between the levels of the fondamental state of ceasium 133 of an atomic clock at rest in ether far from massive objects.
		That means that the one-way velocity of the hypersound-waves is set to 299,792,458 m/s in the rest frame like the French BIPM (Sèvre) defined it for light in any frame and on basis of the erroneous theory of " relativity ".
		The relative second is equal to 9,192,631,770 periods of the hyperfine transition between the levels of the fondamental state of ceasium 133 of an atomic clock in motion in ether at the absolute velocity v measured in the rest frame.
	pages.sbcglobal.net /webster.kehr/DeWitte/met.htm (467 words)

	Observable Characteristics of Extraterrestrial Technological Civilizations
		A circurnstellar nuclear fuel molecular effusion cloud, the principal observable, rapidly dissociates and neutralises to the atomic ground state, permitting the detection of hydrogen and tritium hyperfine transition radio lines at 1420 MHz and 1516 MHz, respectively.
		The spontaneous magnetic dipole hyperfine transition is the only plausible observational characteristic of an artificial, -neutral atomic gas cloud of hydrogen or helium isotopes in the ground state.
		Thus the neutral hydrogen ground-state hyperfine transition line at 1420.405 751 768(3) MHz [55] and the neutral tritium ground-state hyperfine line at 1516.701 9064(16) MHz [56] are the two most promising observational candidates.
	www.rfreitas.com /Astro/ObservableETC1985.htm (6380 words)

	Atomic Clock Based on Opto-Electronic Oscillator
		In atomic clocks of a type known as Raman clocks or coherent-population-trapping (CPT) clocks, microwave outputs are obtained from laser beams modulated, in each case, to create two sidebands that differ in frequency by the amount of a hyperfine transition in the ground state of atoms of an element in vapor form in a cell.
		The components of light scattered or transmitted by the atoms in the two hyperfine levels mix in the photodetector and thereby give rise to a signal at the hyperfine-transition frequency.
		The laser would be chosen to have the same wavelength as that of the pertinent ground-state/higher-state transition of the atoms in the vapor.
	www.nasatech.com /Briefs/Apr05/NPO30557.html (580 words)

	The Australian National University <ADT> Public View
		The very long T_1 (~weeks [4]) observed for rare-earth hyperfine transitions appears promising but hyperfine T_2s were only a few ms, comparable to rare earth optical transitions and therefore the usefulness of such proposals was doubtful.
		The critical point technique is the application of a static magnetic field such that the Zeeman shift of the hyperfine transition of interest has no first order component, thereby nulling decohering magnetic interactions to first order.
		Using the critical point technique results in a hyperfine state that is inherently insensitive to small magnetic field perturbations and therefore more robust for QIP applications.
	thesis.anu.edu.au /public/adt-ANU20061010.124211/index.html (736 words)

	PRS10 - Rubidium Frequency Standard
		All commercial rubidium frequency standards operate by disciplining a crystal oscillator to the hyperfine transition at 6.834,682,612 GHz in rubidium.
		The crystal oscillator is stabilized to the rubidium transition by detecting the light dip while sweeping an RF frequency synthesizer (referenced to the crystal) through the transition frequency.
		Manufacturers of rubidium frequency standards sometimes use a crystal frequency that is an exact sub-multiple of the hyperfine transition frequency in order to simplify the design of the RF frequency synthesizer.
	www.thinksrs.com /products/PRS10.htm (1111 words)

	BIPM - second
		Experimental work, however, had already shown that an atomic standard of time, based on a transition between two energy levels of an atom or a molecule, could be realized and reproduced much more accurately.
		periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom.
		(hfs Cs), is used to denote the frequency of the hyperfine transition in the ground state of the caesium atom.
	www.bipm.fr /en/si/base_units/second.html (292 words)

	A Search for the Tritium Hyperfine Line from Nearby Stars
		A search for the tritium hyperfine line at 1516 MHz from 108 assorted astronomical objects, with emphasis on 53 nearby stars, was conducted in June 1983.
		The neutral tritium ground-state hyperfine transition line at 1516.701470 9064(16) MHz (Mathur et al., 1967) is centered in the SETI waterhole region of the terrestrial microwave window (Billingham and Oliver, 1973) which lies between the H and OH spectral lines.
		A search centered on the tritium hyperfine line for 108 assorted astronomical objects, with emphasis on 53 nearby stars, was conducted from 28 June to 10 July 1983 using the 26-m radiotelescope at the University of California's Hat Creek Radio Observatory, located about 270 miles north of the Berkeley, California, campus.
	www.rfreitas.com /Astro/TritiumSearch1986.htm (1677 words)

Try your search on: Qwika (all wikis)