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Topic: Nuclear spin

	Nuclear Spin
		The half-integer spins of the odd-A nuclides suggests that this is the nuclear spin contributed by the odd neutron.
		Associated with each nuclear spin is a magnetic moment which is associated with the angular momentum of the nucleus.
		It is common practice to express these magnetic moments in terms of the nuclear spin in a manner parallel to the treatment of the magnetic moments of electron spin and electron orbital angular momentum.
	hyperphysics.phy-astr.gsu.edu /hbase/nuclear/nspin.html (659 words)

	Spin (physics) - Wikipedia, the free encyclopedia
		The spin of composite particles, such as protons, neutrons, atomic nuclei, and atoms, is made up of the spins of the constituent particles, and their total angular momentum is the sum of their spin and the orbital angular momentum of their motions around one another.
		This is understood to refer to the spin of the lowest-energy internal state of the composite particle (i.e., a given spin and orbital configuration of the constituents).
		Spin was first discovered in the context of the emission spectrum of alkali metals.
	en.wikipedia.org /wiki/Spin_(physics) (2072 words)

	NIST: Methane Symmetry Operations - Nuclear spin functions
		Spin functions, whether electronic or nuclear, must of necessity be handled somewhat formally, since the introduction of spin "variables" does not facilitate the mathematical representation of observed physical phenomena.
		Most frequently, nuclear spin functions are considered in which projections are taken along the laboratory-fixed Z axis, and for simplicity we shall consider only that case here.
		Because laboratory-fixed nuclear spin functions are analogues of positional functions of laboratory-fixed coordinates of individual particles, it is possible to apply permutation-inversion operations to them directly [see equation (eq.
	physics.nist.gov /Pubs/Methane/chap09.html (405 words)

	Nuclear Magnetic Resonance
		When the nuclear magnetic moment associated with a nuclear spin is placed in an external magnetic field, the different spin states are given different magnetic potential energies.
		Note that the electron spin magnetic moment is opposite to the electron spin while the proton spin magnetic moment is in the direction of the proton spin.
		The Larmor frequency of the electron spin is in the microwave region of the electromagnetic spectrum and is used in electron spin resonance.
	hyperphysics.phy-astr.gsu.edu /hbase/nuclear/nmr.html (523 words)

	l1
		Nuclear spin angular momentum is quantized (as is all angular momentum) and restricted to integral or half integral values.
		In this experiment the nuclear spins are excited by a short burst of light (radiofrequency) and the resultant excited states produce a magnetic field which is detected (the Free induction decay).
		20 describes the motion of a single nuclear spin in the rotating co-ordinate frame under the influence of the static magnetic field.
	www.intermnet.ua.es /inteRMNet/cursoRule/l1.html (1343 words)

	CHEMISTRY: Nuclear Spin Conversion in Molecules -- Hougen and Oka 310 (5756): 1913 -- Science (Site not responding. Last check: 2007-09-07)
		The concept of nuclear spin modifications in molecules (1) is intriguing to chemists because interconversion between different spin states is often slow enough to be considered negligible for many purposes.
		This remarkable stability of a single spin modification was ascribed by Wigner to the smallness of the nuclear spin interaction term that mixes ortho and para states (4).
		nuclear spin pairs, and the E nuclear spin functions do not cluster, one can further speculate (9) that conversion rates within the nuclear spin A species or within the B species will be much faster than rates between A and E or between B and E species.
	www.sciencemag.org /cgi/content/full/310/5756/1913 (1500 words)

	NMR Spectroscopy
		The difference in energy between the two spin states is dependent on the external magnetic field strength, and is always very small.
		For spin 1/2 nuclei the energy difference between the two spin states at a given magnetic field strength will be proportional to their magnetic moments.
		If an atom under examination is perturbed or influenced by a nearby nuclear spin (or set of spins), the observed nucleus responds to such influences, and its response is manifested in its resonance signal.
	www.cem.msu.edu /~reusch/VirtualText/Spectrpy/nmr/nmr1.htm (6080 words)

	GaAs: Resonant Spin Amplification
		If the pump pulses are applied resonantly with the nuclear spin precession frequency, this field leads to a tipping of the nuclear spins, which can again be monitored by the electron spin precession frequency.
		Manipulation of the nuclear spin states in semiconductors is possible through the hyperfine interaction with electron spins.
		the population of the upper spin state is made equal to that of the lower state), such flip-flop processes try to reestablish thermal equilibrium, resulting in a nuclear spin polarization which is described by a Boltzman factor where the electron Zeeman splitting enters.
	www.physics.ucsb.edu /~awschalom/research/NMR.html (536 words)

	Meacher condemns pro-nuclear 'spin' \| Special reports \| Guardian Unlimited
		Sir David warned yesterday that a declining role for nuclear power was contributing to the government's failure to meet its targets on reducing carbon dioxide emissions, and that faced with the reality of global warming, "the equation is simple".
		A move to commission a new generation of nuclear reactors as Britain's existing ones are decommissioned would put Mr Blair on a collision course with most environmentalists and many Labour party members.
		She said nuclear power was not the "awful option" it had once been seen as, and had been proved to be safe.
	www.guardian.co.uk /nuclear/article/0,2763,1647640,00.html (733 words)

	CHAPTER-3
		In nuclear magnetic resonance, it is unpaired nuclear spins that are of importance.
		The signal in NMR spectroscopy results from the difference between the energy absorbed by the spins which make a transition from the lower energy state to the higher energy state, and the energy emitted by the spins which simultaneously make a transition from the higher energy state to the lower energy state.
		It is possible to change the net magnetization by exposing the nuclear spin system to energy of a frequency equal to the energy difference between the spin states.
	www.cis.rit.edu /htbooks/mri/chap-3/chap-3.htm (2800 words)

	ReviseMRI.com : Nuclear spin
		Spin is a quantum mechanical intrinsic property of elementary particles.
		However, it is wise to separate this notion of a spinning particle from the quantum mechanical property we call "spin".
		Although spin is a form of angular momentum, an elementary particle with spin does not mean it is rotating; particles with spin simply have spin.
	www.revisemri.com /questions/basicphysics/spin (387 words)

	Magnetic Resonance TIP - MRI Database : 'Spin' (Site not responding. Last check: 2007-09-07)
		The NMR, MRI relevant nuclear spin is the rotational movement of a subatomic particle (proton or neutron) around its axis.
		This spin is measured with a nuclear spin quantum number (I).
		The nuclear spin quantum number of a nuclei depends on the protons/neutrons which are not paired, and is a positive integer multiple of 0.5.
	www.mr-tip.com /serv1.php?type=db1&dbs=Spin (733 words)

	Patient stress is conjured in newest generation of open-sided nuclear spin tomographs (Site not responding. Last check: 2007-09-07)
		The newly designed family of nuclear spin tomographs has the aspect of a Grecian temple, a magical place for meditation as it seems, which can equally be applied for image-aided surgical interventions.
		Some fifteen years ago, nuclear spin tomography was introduced in Germany as a revolutionary method of diagnostic medical imaging.
		Unlike X-rays, the use of nuclear spin tomography causes no negative side effects, since the imaging is performed via magnetic fields and radio waves.
	www.hoise.com /vmw/99/articles/vmw/LV-VM-01-99-28.html (596 words)

	Nuclear shapes
		Nuclear structure research with exotic as well as stable nuclear beams is in an exciting and evolving challenge.
		In deformed axially symmetric nuclei, isomers occur when there is a secondary minimum for a certain value of K, the projection of the total nuclear spin along the symmetry axis of the nucleus (fig 3).
		The characteristic picket fence gamma-ray pattern of a rotational band was observed for spins as high as 60' and the measurement of the quadrupole moment indicates a deformation with an axis ratio of 2:1.
	www.europhysicsnews.com /full/07/article1/article1.html (2991 words)

	EPR continuous wave endor page
		ENDOR (Electron Nuclear Double Resonance) is a double resonance technique that combines the high resolution and nuclear selectivity of an NMR experiment with the sensitivity of an EPR experiment.
		S and I are the electron and nuclear spin operators respectively and A is the hyperfine matrix.
		I is the nuclear spin operator and P is the quadrupolar interaction matrix.
	www.bruker-biospin.com /brukerepr/continuouswaveendor.html (1845 words)

	Nuclear Magnetic Resonance
		Nuclear magnetic resonance (NMR) of protons in bulk matter was first demonstrated in 1946 independently by F. Bloch and E. Purcell who were jointly awarded the Nobel prize for their discoveries in 1952.
		The unit of nuclear magnetism analogous to the Bohr magneton of atomic physics is the nuclear magneton, µ
		The aldehyde proton spin can be up or down, thus producing two possible values for the magnetic field at the CH protons, as shown in Fig.
	www.breadloaf.middlebury.edu /~PHManual/nuclearmag.html (4090 words)

	All-optical NMR in a single quantum well
		This spin can be divided into two components along and perpendicular to the precession axis.
		Nuclear resonances induced by laser pulses at a repetition rate of 76 MHz.
		At 7.44 T, the nuclear precession frequency of 69Ga matches the repetition rate, leading to depolarization of the nuclear spin.
	www.physics.ucsb.edu /~awschalom/research/QWNMR.html (359 words)

	Introduction to Spintronics
		Spintronics, or spin electronics, refers to the study of the role played by electron (and more generally nuclear) spin in solid state physics, and possible devices that specifically exploit spin properties instead of or in addition to charge degrees of freedom.
		For example, spin relaxation and spin transport in metals and semiconductors are of fundamental research interest not only for being basic solid state physics issues, but also for the already demonstrated potential these phenomena have in electronic technology (some short reviews).
		In addition to the near-term studies of various spin transistors and spin transport properties of semiconductors, a long-term and ambitious subfield of spintronics is the application of electron and nuclear spins to quantum information processing and quantum computation (for more information on quantum computation, check out the following site).
	www.physics.umd.edu /rgroups/spin/intro.html (799 words)

	International Union of Pure and Applied Chemistry
		Nuclear receptivity relative to that of the carbon-13 nucleus
		Nuclear receptivity relative to that of the proton (hydrogen-1 nucleus)
		Nuclear spin-spin coupling constant through n bonds (usually given in frequency units) Parentheses may be used (for example) to indicate the species of nuclei coupled, e.g.
	www.iupac.org /reports/1997/6912harris/symroman.html (447 words)

	EPR: ENDOR
		As each nuclear spin couples to only one electron spin, this spectrum will be greatly simplified compared to the EPR spectrum, while still containing the same information with regard to the hyperfine interaction parameters.
		The observation of the nuclear spin spectrum is realized by the simultaneous irradiation of an electron spin transition and a nuclear spin transition, a technique named Electron-Nuclear Double Resonance (ENDOR).
		The dramatic resolution enhancement achieved by ENDOR results to a large extent from the fact that two resonance conditions have to be fulfilled simultaneously: one for the electron spin transition (EPR) and one for the nuclear spin transition (NMR).
	www.bruker-biospin.de /EPR/articles/endor.html (498 words)

	nuclear scattering/incoherent (Site not responding. Last check: 2007-09-07)
		Nuclear scattering cross sections are listed as coherent and incoherent scattering cross sections.
		The nucleus is a composite fermion with total spin I. The neutron is a fermion with spin 1/2.
		As an example, for Hydrogen the scattering length for a neutron having its spin parallel to the nucleus is +10.82 fm, and for a neutron having its spin anti-parallel it is -47.42 fm.
	www.missouri.edu /~physwww/neutron_scattering/tb/cross-section/nuclear_scattering_incoherent.html (600 words)

	ELECTRON SPIN RESONANCE
		Electron spin exchange between identical and nonidentical molecules, chemical exchange between the paramagnetic molecule and its environment, and the interaction of nearby molecules having unpaired spins are some examples of environmental effects which can influence line width and intensity in the ESR spectrum.
		) interacts with the nuclear spins of two hydrogen atoms on the same carbon atom and also with the three hydrogens of the adjacent methyl group (CH The energy levels of an unpaired electron interacting with two nuclear spins is shown in Figure 1.
		This spin label can be inserted into a cell membrane so each value of n corresponds to a different depth in the membrane, and a sequence of labels provides information on the activities of the membrane at various depths below the surface.
	www.uottawa.ca /publications/interscientia/inter.2/spin.html (2464 words)

	Nuclear Spin Relaxation
		In NMR, a strong magnetic field is used to partially polarize the nuclear spins.
		This "relaxation" back to a state where their spins are parallel to the static magnetic field produces a small amount of RF radiation which is detected as the NMR signal.
		Since the magnetic potential energy is proportional to the projection along this axis, a change in the magnetization along this axis involves the exchange of energy.
	hyperphysics.phy-astr.gsu.edu /hbase/nuclear/spinrel.html (349 words)

	Nuclear Spin - Nuclear Spin
		Because of Blair's conversion to the nuclear cause as well the pro-nuclear bias of the Cabinet, the Energy Review is seen by some as a cynical PR exercise by the government that gives the appearance of a public debate, whilst the decision is already made up.
		The Nuclear Spin website is designed to help people find out more about the individuals involved in the push for new nuclear power stations in the UK.
		Some of them are advocates of nuclear power, while others are key advisors or ministers in government who will be making decisions about nuclear in the coming weeks and months.
	www.nuclearspin.org (584 words)

	Nuclear Physics at the Department of Physics and Astronomy
		Research in nuclear physics at UNC focuses on the nature of the nuclear force, nuclear astrophysics, and fundamental symmetries in nature.
		The Nuclear Astrophysics program at UNC delves into the mysteries of space, searching for answers to the questions posed by phenomena such as solar nuclear reactions, the evolution of the galaxy, and the influence of nuclear processes on the Universe.
		Beams and targets in which the nuclear spin angular momentum is controlled provide sensitive probes of nuclear forces.
	www.physics.unc.edu /research/nuclear (325 words)

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