Pink diamonds captivate sensor researchers

TOKYO - Jewellery aficionados are not the only ones in love with pink diamonds. Researchers in the field of semiconductors and telecommunications are also fascinated by the gemstone for its potential ability to measure temperatures and detect trace amounts of electromagnetic radiation emitted from even a tiny area.

The use of pink diamonds could, for example, lead to smaller versions of the massive MRI machines currently used for medical diagnosis. Japanese researchers are conducting advanced basic research into the gemstone, while those in Western countries are focusing more on applications.

Helpful impurities

Diamond crystals usually consist solely of carbon atoms. When nitrogen impurities are present, holes in the crystal created by missing carbon atoms combine with the nitrogen atoms to form a structure known as a nitrogen-vacancy centre. When sunlight reaches an NV centre inside the diamond, it emits red fluorescence, which makes the stone look pink.

The NV centre is negatively charged and exhibits a property known as electron spin. It has been shown, both theoretically and experimentally, that the fluorescence intensity changes when an NV centre is exposed to both light and magnetism at the same time. This property of pink diamonds is expected to help in detecting localized magnetic fields.

The Japan Science and Technology Agency, a government research body, is working to develop a new type of biomagnetism measuring system using pink diamonds. Mutsuko Hatano, a professor at the Tokyo Institute of Technology, is leading the project, which began in October 2013 and is slated to be completed by March 2019.

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