Higher Harmonic Atomic Force Microscopy: Imaging of Biological Membranes in Liquid
J. Preiner, J. Tang, V. Pastushenko, P. Hinterdorfer - Higher Harmonic Atomic Force Microscopy: Imaging of Biological Membranes in Liquid - PHYSICAL REVIEW LETTERS, 2007
The contribution of higher harmonics to the movement of a dynamic force microscope cantilever
interacting with a sample in liquid was investigated. The amplitude of the second harmonic has been
found to be an order of magnitude higher in liquid than in air, reflecting an increased sensitivity to local
variations in elasticity and interaction geometries. A theoretical model of the tip-sample interactions in
liquid was introduced and shown to be consistent with experimental findings. Second harmonic amplitude
images were recorded on soft biological samples yielding a lateral resolution of 0:5 nm.