From Wikipedia, the free encyclopedia
Nuclear orientation , in
nuclear physics , is the directional ordering of an assembly of
nuclear spins with respect to some axis in space.
[1]
[2] It is one of the
nuclear spectroscopy methods.
A
nuclear level with
spin in a
magnetic field will divide into magnetic sub-levels with an energy spacing.
[3]
The populations of these levels are determined by the
Boltzmann distribution at a steady temperature and will essentially be equal. The exponential in the Boltzmann distribution should not be equal to 1 to obtain unequal populations. To achieve this, cooling to a temperature of around 10 millikelvin is needed.
Typically, this is achieved by implanting the
nuclei of interest into
ferromagnetic hosts.
In the mid-1940s,
Yevgeny Zavoisky developed
electron paramagnetic resonance , eventually leading to the concept of nuclear orientation.
[4]
In the early 1950s,
Neville Robinson ,
Jim Daniels , and
Michael Grace produced an example of nuclear orientation for the first time at the
Clarendon Laboratory ,
University of Oxford .
[5]
There is now a Nuclear Orientation Group at Oxford.
[3]
Bibliography
K. S. Krane,
Nuclear orientation and nuclear structure .
Hyperfine Interactions , Volume 43, Numbers 1–4, pages 3–14, December, 1988.
doi :
10.1007/BF02398283
B. Bleaney,
Cross-relaxation and nuclear orientation in ytterbium vanadate .
Proceedings: Mathematical, Physical and Engineering Sciences , Volume 455, Number 1988, pages 2835–2839, 8 August 1999. Published by
The Royal Society .
B. Bleaney,
Dynamic nuclear polarization and nuclear orientation in terbium vanadate .
Applied Magnetic Resonance , Volume 21, Number 1, pages 35–38, December, 1988.
doi :
10.1007/BF03162437
See also
References
^
Nuclear orientation ,
The Free Dictionary .
^
Nuclear orientation
Archived 2011-06-17 at the
Wayback Machine ,
AccessScience .
^
a
b
General Idea of Nuclear Orientation ,
Nuclear Orientation Group ,
University of Oxford , UK.
^ B. Bleaney and O. V. Lounasmaa,
Nuclear Orientation and Nuclear Cooling Experiments in Oxford and Helsinki. Part 2. Progress from 1945 to 1970 .
Notes and Records of the Royal Society of London , Volume 57, Number 3, pages 323–330, September 2003. Published by
The Royal Society .
^ Nicholas Kurti,
Obituary: Neville Robinson [
dead link ] .
The Independent , 27 November 1996.