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First observation of 239Pu NMR
-A new frontier for the physics and chemistry of actinide compounds-

May. 18, 2012

[Point of the released]

A team of scientists at the Japan Atomic Energy Agency (JAEA) and Los Alamos National Laboratory (LANL) have detected the faint signal of plutonium-239ís unique nuclear magnetic resonance signature. This signal promises to become a Rosetta Stone for deciphering complex, atomic-scale electronic properties of this perplexing element.

Plutonium is the most complex element in the periodic table, yet it is also one of the most poorly understood. Nuclear magnetic resonance (NMR) spectroscopy, a well-known scientific technique, may turn out to be the perfect tool for uncovering some of plutoniumís mysteries. For more than 50 years, chemists and physicists have been searching for the 239Pu magnetic resonance signal. Only now, a result of the international collaboration between LANL and the JAEA, scientists determined just the right conditions for observing the signal. The team, led by visiting professor Hiroshi Yasuoka (JAEA) observed the 239Pu resonance from a high purity solid sample of plutonium dioxide, at a temperature of 4 Kelvin as a function of magnetic field.

The team determined the important physical constant (gyromagnetic ratio) that will allow future studies of plutonium by this technique. This constant is a fingerprint of plutoniumís nucleus, but it allows scientists also to study its electrons. These electrons play a decisive role in controlling the metallurgy and chemical reactivity of plutonium alloys and compounds. They are crucial to determining the structural instability of elemental plutonium itself, the formation of molecular complexes as plutonium interacts with the environment and biological matter, and even the creation of unconventional superconductivity.

In view of the importance of plutonium compounds for nuclear fuels, environmental behavior, long-term storage of nuclear wastes, and power generation for interplanetary exploration, the ability to explore plutonium materials using NMR should prove particularly powerful.

Collaborators of Yasuoka in this discovery are Hiroyuki Chudo (JAEA) and Gerogios Koutroulakis, Eric D. Bauer, David L. Clark, Gordon D. Jarvinen, Scott Richmond, Alice I. Smith, Joe D. Thompson, and Douglas K. Veirs ( LANL).

This paper on the subject, "Observation of 239Pu Nuclear Magnetic Resonance", has been published in the 18 May, 2012 issue of Science magazine, and selected as one of the highlights in this issue.

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