Development of an Atomic Force Microscope and Nano-Indenter with a Magnetically Levitated Tip for Research and Education

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Manias

The introduction of the Atomic Force Microscope (AFM) has revolutionized the research of surfaces at the nanometer length scale by facilitation many new and versatile surface exploration approaches. However, the use of a metal cantilever to support the scanning tip -explicit in all AFMs- is responsible for a number of instabilities and limitations. The development of a magnetically levitated tip will eliminate these instabilities caused by the cantilever spring (such as abrupt snaps of the tip into the sample -jump-to-contact) and limitations in operation (for example the force modulation technique is limited to the studies of samples with surface elasticity comparable to the cantilever spring constant). At the same time the new system will provide several new measurement capabilities beyond the ones available in conventional AFMs: (1) ability to measure tip-surface interactions down to atomic contact, and thus provide accurate quantitative determination of intermolecular forces and adhesion; (2) versatility in attaching any 'tip' without being limited by shape, size, or material, furnishing great adaptability to specific experimental needs; (3) direct magnetic force applied to the tip -over mm distance and in magnitudes greatly exceeding any current AFM performance- rendering it a very powerful nanoindenter, and; (4) ability to tune -in situ- the resonance frequency of vibration and apply direct force modulation to the tip, providing unmatched sensitivity in force modulation studies, and enabling the study of samples with surface modulus inhomogeneities, and samples undergoing transitions.

This AFM/Nanoindenter equipped with the magnetically levitated tip will be integrated in the user facilities of the Mateials Characterization Lab (MCL), and will be located in the building of the Materials Research Institute. The MCL provides analytical services, specialized instruments, personnel and expertise in materials characterization in support of research and training throughout the Pennsylvania State University, with a strong emphasis in surface charactierization. At the same time, researchers, especially graduate and undergraduate students, are trained to use facilities and instrumentation.

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This instrumentation is expected to significantly enhance research, as well as training of students.

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