Resumen de Determination of nanomechanical properties of surfaces by atomic force microscopy using higher harmonics
The increasing engineered miniaturization of objects, one of the salient features of Nanotechnology, has driven great interest towards the mechanical properties of materials at the nanoscale. Many examples can be found in the literature, including nanoparticles, thin films, nanostructures, etc. Among the variety of available experimental methods to characterize such properties we have chosen atomic force microscopy (AFM). The advantage of AFM over other experimental techniques is that it permits the parallel determination of the topography of surfaces and of nanomechanical properties such as energy dissipation, through phase images, adhesion and surface stiffness. Within the dynamic modes of operation we have chosen the amplitude modulation (AM-AFM) mode using more than one characteristic frequency of the oscillating cantilever, what is known as the multifrequency approach. In particular we have chosen the case where flexural eigenmodes of the cantilever are in close resonance with higher harmonics, which are excited in the tip/surface repulsive regime of interaction due to the nonlinear character of such interactions. The use of higher harmonics to characterize the nanomechanical properties of surfaces is not new but here we have managed to provide quantitative information of such properties choosing polymers of interest in micro/nanoelectronics as test materials.
