Scanning probe microscopy (SPM) covers several related technologies for imaging and measuring surfaces on a fine scale, down to the level of molecules and atoms. SPM technologies share the concept of scanning an extremely sharp tip (3-50 nm radius of curvature) across the object surface. The tip is mounted on a flexible cantilever, allowing the tip to follow the surface profile. When the tip moves in proximity to the investigated object, forces of interaction between the tip and the surface influence the movement of the cantilever.  These movements are detected by selective sensors. Various interactions can be studied depending on the mechanics of the probe.

The three most common scanning probe techniques are:

Atomic Force Microscopy (AFM) measures the interaction force between the tip and surface. The tip may be dragged across the surface, or may vibrate as it moves.  The interaction force will depend on the nature of the sample, the probe tip and the distance between them.

Scanning Tunneling Microscopy (STM) measures a weak electrical current flowing between tip and sample as they are held a very distance apart.

Near-Field Scanning Optical Microscopy (NSOM) scans a very small light source very close to the sample.  Detection of this light energy forms the image.  NSOM can provide resolution below that of the conventional light microscope.

In the lab, we use Pacific Nanotechnology Scanning Probe Microscope (SPM) to probe the interactions between the tip and the specimen in contact mode or non-contact mode.

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