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Microdiamonds with nitrogen vacancy centers are increasingly used as biological tracers thanks to the optical fluorescence of NV centers. But the NV centers also can be spin-polarized by low-power lasers, and the polarized centers then polarize nearby carbon-13 atoms occurring naturally in the diamonds. These hyperpolarized C-13 atoms can be detected by NMR imaging. Chemists now demonstrate dual-mode imaging with NV-center diamonds, potentially allowing high-quality imaging 10 times deeper than with optics alone.