THE ATOMIC-FORCE MICROSCOPE AS A NEAR-FIELD PROBE FOR ULTRASOUND

An atomic force microscope was modified such that vibrations in the MHz regime could be detected at the backside of the cantilever. The sample was insonified by an ultrasonic transducer attached to it. Images with atomic resolution were obtained on a mica surface. The lowest resonance frequency of cantilevers is usually several kHz. Nevertheless, ultrasonic vibrations of high amplitude with frequencies of 1-15 MHz can be transmitted to cantilevers by exciting flexural vibrations. The propagation of the ultrasonic waves in the cantilever and their transmission from the sample surface to the cantilever are discussed, taking into account non-linear effects.