Abstract
Using atomic force microscopy (AFM/SFM), the strength of the adhesion between nanoparticles (NPs) and a flat gold surface was studied. By scanning in contact mode, a lateral force was applied to the NPs, depending on the cantilever stiffness and the setpoint value of the topography feedback. In this way, a threshold force for NP detachment was determined. The sample under investigation consisted of arrays of tungsten NPs deposited on top of a flat gold surface. The NPs were generated using electron beam deposition (EBD) and the precursor gas W(CO)~6~. Owing to the arrayβwise arrangement of the NPs, any change in their position was comparatively easy to detect by deviation from the array points. The beam dwell time was employed as a parameter to control the NP size. The force threshold value for particle detachment was found to increase with the beam dwell time. Loose NPs moved by the scanning tip displayed increased lateral forces. These appeared in the lateral force images as continuous tracks. After expansion of the scan area such tracks were seen to mostly originate from the edges of the previous scans where the NPs had piled up. (Β© 2008 WILEYβVCH Verlag GmbH & Co. KGaA, Weinheim)