Theoretical investigation on force sensitivity in Q-controlled phase-modulation atomic force microscopy in constant-amplitude mode.

We theoretically investigate the force sensitivity of phase-modulation atomic force microscopy in the constant amplitude mode with Q-control technique, which enables to increase or decrease the effective Q factor (Qeff) of the cantilever. The relation between the minimum detectable interaction force and the effective Q factor is derived from the equation of motion for the cantilever at low Q environment such as liquid environment. It indicates that the minimum detectable interaction force can be reduced in proportion to Qeff1/2 under strong Q enhancement, while it does not depend on the effective Q factor under weak Q enhancement. [ABSTRACT FROM AUTHOR]