WSxM: During many years our group has participated actively in the development of WSxM a well known software application for scanning probe microscopy (SPM) data analysis and control [Horcas_07]. It can read most of the commercial file formats. The software can be freely downloaded from Nanotec. Our group has an extended experience in instrumentation: we design, build and use our own AFM prototypes.
Jumping Mode (JM): At the end of the 90’s we developed JM [dePablo_98] as a technique to avoid the high lateral forces presented in contact mode. We rapidly observed that the main application of JM was scanning under liquids [Moreno-Herrero_02]. JM has a clear advantage over dynamic modes: the images are much easy to understand and intrepret [Moreno-Herero_04]
3D modes: within the frame of WSxM we created a scanning tool that allows representing a magnitude as a function of 2 other independent ones [Gomez-Navarro_02_2]. The image displays the variation of the amplitude of oscillation of a cantilever as a function of the tip sample distance and the oscillation frequency originated by the electrostatic interaction. As the tip approaches the metallic surface the resonance frequency drops.
Ferromagnetism in graphite steps. Theoretical and experimental results suggest that carbon based material may exhibit ferromagnetism. A work published in Nat. Phys. (Cervenka_09) reported magnetic force microscopy images exhibiting clear contrast along the graphite steps. We have developed a technique, based on frequency modulation and kelvinprobe force microscopy, that allows separating the electrostatic and magneticsinteractions that an AFM tip can experiment simultaneously. Our results suggest that the origin of the signal along the graphite steps is electrostatic and not magnetic. [Martinez-Martin_10]
Dynamic AFM modes in liquids: in collaboration with Prof. Arvin Raman we are now working on understanding amplitude modulation (AM-AFM) (cita peak forces, liquids cell, PNAS) and frequency modulation (FM-AFM) in physiological conditions. These study arevery relevant for imaging biological material. The image shows true atomic resolution of a mica surface immersed in a buffer solution.