title: Electron spin resonance of nitrogen-vacancy centers in optically trapped nanodiamonds.
abstract: Using an optical tweezers apparatus, we demonstrate three-dimensional control of nanodiamonds in solution with simultaneous readout of ground-state electron-spin resonance (ESR) transitions in an ensemble of diamond nitrogen-vacancy color centers. Despite the motion and random orientation of nitrogen-vacancy centers suspended in the optical trap, we observe distinct peaks in the measured ESR spectra qualitatively similar to the same measurement in bulk. Accounting for the random dynamics, we model the ESR spectra observed in an externally applied magnetic field to enable dc magnetometry in solution. We estimate the dc magnetic field sensitivity based on variations in ESR line shapes to be approximately 50 μT/√Hz. This technique may provide a pathway for spin-based magnetic, electric, and thermal sensing in fluidic environments and biophysical systems inaccessible to existing scanning probe techniques.
authors.affiliation: Department of Physics, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Viva R
authors.initials: VR
authors.lastname: Horowitz
authors.forename: Benjamín J
authors.initials: BJ
authors.lastname: Alemán
authors.forename: David J
authors.initials: DJ
authors.lastname: Christle
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Cleland
authors.forename: David D
authors.initials: DD
authors.lastname: Awschalom
mesh_terms: D001672:Biocompatible Materials / Q000737:chemistry; D001703:Biophysics / Q000379:methods; D015374:Biosensing Techniques; D004578:Electron Spin Resonance Spectroscopy; D004867:Equipment Design; D004926:Escherichia coli / Q000378:metabolism; D008280:Magnetics; D008390:Markov Chains; D008872:Microwaves; D009038:Motion; D058612:Nanodiamonds / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D052898:Optical Tweezers; D055095:Optics and Photonics; D011336:Probability; D013696:Temperature
chemical_list: D001672:Biocompatible Materials; D058612:Nanodiamonds