NOISE-REDUCTION IN ATOMIC-FORCE MICROSCOPY - RESONANCE CONTACT MODE

Noise reduction has been accomplished in atomic force microscopy by ap plying a high frequency, low amplitude vibration to the cantilever whi le it is in contact with a surface. The applied excitation (>200 kHz; similar to 1 nm) is acoustically coupled to the tip and dampens the re sonance Q factors of the system. The applied frequency is well above t he bandwidth of the acquisition system (50 kHz). We call this mode ''r esonance contact'' mode. The nonlinear behavior of the tip-sample inte raction allows the high frequency excitation to effectively broaden th e frequency response of the system resonances. (C) 1996 American Insti tute of Physics.