  We report on precise localization spectroscopy experiments of individual 13C
nuclear spins near a central electronic sensor spin in a diamond chip. By
detecting the nuclear free precession signals in rapidly switchable external
magnetic fields, we retrieve the three-dimensional spatial coordinates of the
nuclear spins with sub-Angstrom resolution and for distances beyond 10
Angstroms. We further show that the Fermi contact contribution can be
constrained by measuring the nuclear g-factor enhancement. The presented method
will be useful for mapping the atomic-scale structure of single molecules, an
ambitious yet important goal of nanoscale nuclear magnetic resonance
spectroscopy.
