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Register a new userEstimation of friction force in an oscillator model of atomic force microscope tip sliding on vibrating surface
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Added by
Elena Kazantseva V.
Publication date
2020
fields
Physics
and research's language is
English
Authors
E. V. Kazantseva
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We consider an oscillator model to describe qualitatively friction force for an atomic force mi-croscope (AFM) tip driven on a surface described by periodic potential. It is shown that average value of the friction force could be controlled by application of external time-dependent periodic perturbation. Numerical simulation demonstrates significant drop or increase of friction depending on amplitude and frequency of perturbation. Two different oscillating regimes are observed, they determined by frequency and amplitude of perturbation. The first one is regime of mode locking at frequencies multiple to driving frequency. It occurs close to resonance of harmonic perturbation and driving frequencies. Another regime of motion for a driven oscillator is characterized by aperiodic oscillations. It was observed in the numerical experiment for perturbations with large amplitudes and frequencies far from oscillator eigenfrequency. In this regime the oscillator does not follow external driving force, but rather oscillates at several modes which result from interaction of oscillator eigenmode and perturbation frequency.
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In this activity, students will make a working model of an atomic force microscope (AFM). A permanent magnet attached to a compact disc (CD) strip acts as the sensor. The sensor is attached to a base made from Legos. Laser light is reflected from the CD sensor and onto a sheet of photosensitive paper. An array of permanent magnets attached to cardboard acts as the atoms on a surface. When the sensor is brought near this atomic surface the magnets will deflect the sensor, which in turn deflects the reflected laser. This deflection is recorded on the photosensitive paper, which students can take home with them.
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