Nanoscale nuclear magnetic resonance with a 1.9-nm-deep nitrogen-vacancy sensor.

We present nanoscale nuclear magnetic resonance (NMR) measurements performed with nitrogen-vacancy (NV) centers located down to about 2 nm from the diamond surface. NV centers were created by shallow ion implantation followed by a slow, nanometer-by-nanometer removal of diamond material using oxidative etching in air. The close proximity of NV centers to the surface yielded large ¹H NMR signals of up to 3.4 μT-rms, corresponding to ~330 statistically polarized or ~10 fully polarized proton spins in a (1.8 nm)³ detection volume. [ABSTRACT FROM AUTHOR]