  The detection of individual molecules and their dynamics has been a
long-standing challenge in the field of nanotechnology. In this work, we
present a method that utilizes a nitrogen vacancy (NV) center and a
dangling-bond on the diamond surface to measure the coupling between two
electronic targets tagged on a macromolecule. To achieve this, we design a
multi-tone dynamical decoupling sequence that leverages the strong interaction
between the nitrogen vacancy center and the dangling bond. In addition, this
sequence minimizes the impact of decoherence finally resulting in an increased
signal-to-noise ratio. This proposal has the potential to open up new avenues
for fundamental research and technological innovation in distinct areas such as
biophysics and biochemistry.
