AFM - from noncontact imaging, measuring of short-range chemical bonding forces at low temperatures to nanomechanics by cantilevers

H.-J. Guentherodt

Hans-Joachim.Guentherodt@unibas.ch
Department of Physics and Astronomy,
University of Basel, CH 4056 Basel, Switzerland

Noncontact AFM (Atomic Force Microscopy) or SFM (Scanning Force Microscopy) opened a new field of true atomic resolution and allowed the observation of defects and vacancies. A low temperature SFM operating in a dynamic mode in ultra high vacuum was used to study the Si(111)7x7 surface at 7.2K. Not only the twelve adatoms but also the six rest atoms of the unit cell are clearly resolved. These images are of the quality comparable to STM.
The performance of this instrument allows the direct measurement of short-range chemical bonding forces acting between the foremost atom on the apex of a silicon cantilever tip and specific atomic sites on a Si(111)7x7 sample.
There are several characterisitc features of cantilevers making AFM based devices very appropriate for use as a sensor for stress, heat and mass. Examples are Nanocalorimeter, a cantilever array-based artificial nose, the translating of biomolecular recognition into nanomechanics, mechanical data storage by the millipede and the mechanical detection of NMR.