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We have developed a simple tapping mode in atomic force microscopy using a capacitive electrostatic force. In this technique, the probe-to-sample distance is modulated by the capacitive force between tip and sample induced by a sinusoidal bias applied to the conductive probe instead of a conventional mechanical vibration. The electrostatic force versus distance curve of the probe indicates that it is necessary to use a rather stiff cantilever to prevent the snapping of the tip into the surface due to the adhesive force at the surface. We have succeeded in obtaining topographic images of a conductive surface as well as a soft polystyrene sample with a low tracking and lateral force through this method.

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Articles you may be interested inAtomic force microscope in liquid with a specially designed probe for practical application Rev. Sci. Instrum. 76, 053705 (2005); 10.1063/1.1897672High-resolution nanowire atomic force microscope probe grownby a field-emission induced process Although scanning probe microscopy is traditionally limited to slow temporal response, techniques utilizing nonlinear tip-to-sample interactions can be used to capture very fast temporal signals. We have developed a scanning force microscope probe which makes use of these techniques for measuring ultrafast voltage signals with both picosecond time resolution and nanometer-scale lateral resolution. Measurements of very large scale integrated and microwave integrated circuits are shown.

A 20-GHz dielectric-resonator/optical modulator is developed and used as an FM mode locker at the 84th harmonic of a conventional 238-MHz diode-pumped Nd:BEL laser cavity. Depending on the mode-locker drive frequency, two distinct regimes of mode locking were observed: 2.9-ps pulses at a repetition rate of 238 MHz and 3.9-ps pulses at a repetition rate of 20 GHz. These are to our knowledge the shortest pulses ever reported for active mode locking of a Nd laser.