A way to operate fundamental mode amplitude modulation atomic force microscopy is introduced which optimizes stability and resolution for a given tip size and shows negligible tip wear over extended time periods ( 24 h). In small amplitude smal l set-point (SASS) imaging, the cantilever oscillates with sub-nanometer am plitudes in the proximity of the sample, without the requirement of using large drive forces, a s the dynamics smoothly lead the tip to the surface through the water layer. SASS is demonstrat ed on single molecules of double-stranded DNA in ambient conditions where sharp silicon tips (R 2–5 nm) can resolve the right-handed double helix

Peer Reviewed