  The magnetic properties of a monolayer of Mn12 single molecule magnets
grafted onto a Si substrate have been investigated using depth-controlled
$\beta$-detected nuclear magnetic resonance. A low energy beam of spin
polarized radioactive 8Li was used to probe the local static magnetic field
distribution near the Mn12 monolayer in the Si substrate. The resonance
linewidth varies strongly as a function of implantation depth as a result of
the magnetic dipolar fields generated by the Mn12 electronic magnetic moments.
The temperature dependence of the linewidth indicates that the magnetic
properties of the Mn12 moments in this low dimensional configuration differ
from bulk Mn12.
