Resonance frequency and Q factor mapping by ultrasonic atomic force microscopy

We developed an improved ultrasonic atomic force microscopy (UAFM) for mapping resonance frequency and Q factor of a cantilever where the tip is in linear contact with the sample. Since the vibration amplitude at resonance is linearly proportional to the Q factor, the resonance frequency and Q factor are measured in the resonance tracking mode by scanning the sample in the constant force mode. This method enables much faster mapping of the resonance frequency and Q factor than the previous one using a network analyzer. In this letter, we describe the principle and instrumentation of the UAFM and show images of carbon-fiber-reinforced plastic composites. (C) 2001 American Institute of Physics.