Sushkov, AlexanderChisholm, N.Lovchinsky, I.Kubo, M.Lo, P. K.Bennett, StevenHunger, D.Akimov, AlexeyWalsworth, RonaldPark, H.Lukin, Mikhail2017-08-072014Sushkov, A. O., N. Chisholm, I. Lovchinsky, M. Kubo, P. K. Lo, S. D. Bennett, D. Hunger, et al. 2014. “All-Optical Sensing of a Single-Molecule Electron Spin.” Nano Lett. 14 (11) (November 12): 6443–6448. doi:10.1021/nl502988n.1530-6984http://nrs.harvard.edu/urn-3:HUL.InstRepos:33719347We 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.en-USNitrogen vacancy centerdiamondsingle-molecule spinmagnetometryall-opticalJournal Article2017-08-0710.1021/nl502988n