Dynamical characterization of vibrating AFM cantilevers forced by photothermal excitation

The detailed characterization of the dynamical behavior of an oscillating cantilever is a crucial task in many applications of scanning probe microscopy, force spectroscopy, and cantilever based biosensors. In the present work we considered a direct and localized excitation of the cantilever obtained using the photothermal effect induced by a modulated laser beam that allows us to completely separate the dynamics of the system from spurious effects. We developed a theoretical model able to describe the experimental results with high accuracy; in particular, a good agreement is achieved, both for amplitude and phase, in the presence of resonances and antiresonances, depending on the different location of the excitation beam.