Diamond spectroscopy of molecules - spin pair steps

With recent reports on the sensing of electron spins and nuclear spins
from single proteins using the nitrogen-vacancy center in diamond, we
attempt to constrain the number of participating spins. This is achieved
by using doubly spin-labeled amino acids. Both room temperature and low
temperature measurements are presented. We also show how one can gauge
the dipolar couplng between a pair of spin labels in the limit of a very
small (<4) amount of molecules [1]. This is an almost mandatory
requirement for sensing spins in more complex (and of interest for
active research) molecules. Finally, we stress the importance of
quantum-assisted methods in reducing the effective measurement time,
which is critical for imaging purposes [2].
[1] L. Schlipf et al., Science Advances 3, 1701116 (2017)
[2] T. Häberle et al., Rev. Sci. Instrum. 88, 013702 (2017)