Improvements in AFM imaging of the spatial variation of force-distance curves: On-line images

A new scanning method, 'touch and lift', aimed to improve the simultaneous acquisition of topography and force-distance curves on each point of the scanned surface, is presented. This method does not damage the sample or the cantilever and enables us to collect a lot of data in a relatively short time. Its most important feature is that data are directly organized in 'force-slices', i.e. images giving immediate qualitative information on the physico-chemical structure of the sample. We present and discuss such images for two samples: a fluorescein isothyocyanate grating on silicon in air and a peroxidase grating on silicon in water, measuring the spatial variation of stiffness, attractive forces and adhesion in both cases.