ADHESION FORCE IMAGING IN AIR AND LIQUID BY ADHESION MODE ATOMIC-FORCE MICROSCOPY

A new imaging mode for the atomic force microscope (AFM), yielding ima ges mapping the adhesion force between tip and sample, is introduced. The adhesion mode AFM takes a force curve at each pixel by ramping a p iezoactuator, moving the silicon-nitride tip up and down towards the s ample. During the retrace the tip leaves the sample with an adhesion d ip showing up in the force curve. Adhesion force images mapping parame ters describing this adhesion dip, such as peak value, width, and area , are acquired on-line together with the sample topography. Imaging in air gives information on the differences in hydrophobicity of sample features. While imaging a mercaptopentadecane-gold layer on glass in d emineralized water, the adhesion force could be modulated by adding ph osphate buffered saline.