STUDIES OF VIBRATING ATOMIC-FORCE MICROSCOPE CANTILEVERS IN LIQUID

An atomic force microscope (AFM) design providing a focused spot of or der 7 mu m in diameter ws used to analyze the motion of vibrating cant ilevers in liquid. Picking an operating frequency for lapping mode AFM operation in liquid is complex because there is typically a large num ber of sharp peaks in the response spectrum of cantilever slope amplit ude versus drive frequency. The response spectrum was found to be a pr oduct of the cantilever's broad thermal noise spectrum and an underlyi ng fluid drive spectrum containing the sharp peaks. The geometrical sh ape of transverse cantilever motion was qualitatively independent of t he fluid drive spectrum and could be approximately reproduced by a sim ple theoretical model, The measurements performed give new insights in to the behavior of cantilevers during tapping mode AFM operation in Li quid. (C) 1996 American Institute of Physics.