  We investigate the modification of photoluminescence (PL) from single
semiconductor nanocrystal quantum dots (NCs) in proximity of metal and
semiconducting Atomic Force Microscope (AFM) tips. The presence of the tip
alters the radiative decay rate of an emitter via interference and opens
efficient non radiative decay channels via energy transfer to the tip material.
These effects cause quenching (or enhancement) of the emitter's PL intensity,
as a function of its distance from the interacting tip. We take advantage of
this highly distance dependent effect to realize a contrast mechanism for high
resolution optical imaging. AFM tips are optimized as energy acceptors by
chemical functionalization with InAs NCs to achieve optical resolution down to
30 nm. The presented experimental scheme offers high resolution optical
information while maintaining the benefits of traditional AFM imaging. We
directly measure the PL intensity of single NCs as a function of the tip
distance. Our results are in good agreement to calculation made by a classical
theoretical model describing an oscillating dipole interacting with a planar
mirror.

Chemical Physics;Mesoscale and Nanoscale Physics;Optics