Spin Thermometers

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Science  17 May 2013:
Vol. 340, Issue 6134, pp. 789
DOI: 10.1126/science.340.6134.789-b

Developing sensitive, noninvasive nanoscale thermometry is of great interdisciplinary interest, for example, as a tool for measuring tiny intracellular temperature gradients. Fluorescence-based thermometry provides probes of an appropriate size, but conventional techniques have limited temperature resolution. Toyli et al. use the temperature dependence of the energy levels of defect spins in diamond as a basis for sensitive fluorescence thermometry. The defects are of the type called the nitrogen vacancy (NV) center, previously used in magnetic and electric field sensing. To improve the sensitivity, the researchers extended the spin coherence time using dynamical decoupling; they also showed that the technique worked reliably at temperatures as high as 500 K, whereas a 0.1 K shift was easily resolved. It is expected that the temperature sensitivity can be further improved by extending the coherence times, for example, by using isotopically purified diamond to eliminate the main source of decoherence, 13C. In addition to cellular thermometry, potential thermal sensing applications for NV centers in nanostructured diamond include microfluidic thermometry and scanning thermal microscopy.

Proc. Natl. Acad. Sci. U.S.A. 110, 10.1073/pnas.1306825110 (2013).

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