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Diamond detectors

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6:59pm, February 26, 2008

From Boston, at a meeting of the American Association for the Advancement of Science

Diamond impurities can detect extremely weak magnetic fields. Probes with diamond tips might soon become sensitive enough to track single atomic nuclei in molecules by their magnetism, enabling the observation of atoms' motion during chemical reactions.

Diamond is an all-carbon crystal, consisting mostly of non-magnetic carbon-12. The nuclei of the relatively rare carbon-13, however, are magnetic. Harvard University physicist Mikhail Lukin and his collaborators used the carbon-13 nuclei scattered inside a thin layer of artificial diamond as tiny bar magnets to detect external magnetic fields as weak as 10 nanotesla—about one-five thousandth of the Earth's magnetic field.

Because the orientation of a single carbon-13 nucleus is hard to measure directly, the team devised an approach that takes nuclear magnetic resonance (NMR) down to the atomic level.

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