(American Chemical Society (ACS), 2014) Sushkov, Alexander; Chisholm, N.; Lovchinsky, I.; Kubo, M.; Lo, P. K.; Bennett, Steven; Hunger, D.; Akimov, Alexey; Walsworth, Ronald; Park, H.; Lukin, Mikhail
We demonstrate an all-optical method for magnetic sensing of individual molecules in ambient conditions at room temperature. Our approach is based on shallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal, which we use to detect single paramagnetic molecules covalently attached to the diamond surface. The manipulation and readout of the NV centers is all-optical and provides a sensitive probe of the magnetic field fluctuations stemming from the dynamics of the electronic spins of the attached molecules. As a specific example, we demonstrate detection of a single paramagnetic molecule containing a gadolinium (Gd3+) ion. We confirm single-molecule resolution using optical fluorescence and atomic force microscopy to colocalize one NV center and one Gd3+-containing molecule. Possible applications include nanoscale and in vivo magnetic spectroscopy and imaging of individual molecules.
