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Glossary terms about Surface

The specimen being examined by the probe microscope. Generally a solid.

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32 pages mention Surface

AFM calibration methods
surface Science 323 (3): L314-L318, 1995. 
AFM imaging of surfaces
T., et al. Functionalization of vertically aligned carbon nanotubes with polystyrene via surface initiated reversible addition fragmentation chain transfer polymerization. 
AFM imaging: Interactions between the probe and sample
At very close tip-sample distances (a few angstroms), a strong repulsive force appears between the tip and the sample surface due to the overlap of atomic orbitals. 
AFM papers
L., et al. Recent Advances in Atomic-Force Microscopy of DNA. Scanning 15(5): 296-299, 1993.Journal Link... Umemura, K., Arakawa, H., et al. High-Resolution Images of Cell-surface Using a Tapping Mode Atomic-Force Microscope. 
AFM probe modification
-C. Carbon nanotube tips for surface characterization: Fabrication and properties. 
AFM: Background information
Either the probe or sample is mounted on a piezoelectric scanner which can move in the x,y, and z directions, and is used to raster scan the probe across the sample surface to acquire an image in 3 dimensions. 
Cantilever tuning - only for tapping and non-contact modes
Contact and tapping modes
Most topography is done in this mode. 
Contact mode
Contact mode/ constant force AFM operates by scanning the tip across the sample surface while monitoring the change in cantilever deflection with a split photodiode detector. 
Derivative control
Floating control
Force distance spectroscopy
surface Sciences Reports 59 (1-6): 1-152, 2005. 
How is the Data Displayed?
Image artefacts
The disadvantage of smaller diameter probes is that the pressure applied to the surface and the tip increases for a given imaging force. 
Image Scanning and feedback parameter optimisation - scan rate
Scan rate  
Therefore, by scanning the tip over the surface at either a constant current or height, the record of the vertical tip motion will reflect the surface topography of the sample. 
Laser alignment on cantilever
If not performed properly then a number of artefacts can result including, for example, excessive force being applied to the surface when scanning and optical interference fringes from reflective surfaces can be detected. 
Measuring forces in the tip-sample space
In addition to imaging the surface of samples, another major application of AFM is force spectroscopy. 
Non-contact mode
If a very thin fluid layer is covering a rigid sample, in non-contact mode the tip may be oscillating above the fluid and so the liquid layer and the underlying surface can be imaged. 
Non-contact mode
As the name implies, the (oscillating) tip is set further from the sample surface where it is surrounded by attractive forces, and the tip does not contact the surface at any stage. 
Proportional control (P)
Review articles
surface Science Reports 59(1-6): 1-152, 2005. 
Scanner artefacts
Piezoelectric elements in scanners are used to position the probe tip relative to the sample surface at the nanometer scale with great accuracy. 
Scanning Tunneling Microscopy (STM)
In essence, a reproduction of the sample surface is produced by scanning the tip over the sample surface and sensing the tunnelling current. 
Set point - Tapping mode
If the set-point is too high, then the tapping force is reduced to such a level that the tip may not track the surface properly and move in and out of feedback. 
Set-point - contact mode
Since the force the cantilever exerts on the sample is directly proportional to the deflection of the cantilever via Hooke’s Law, it is possible for the operator to control the amount of force being applied to the sample surface while imaging. 
Specimen choice
Therefore any surface with more than five microns of roughness will be extremely difficult to image with most AFMs. 
Tapping mode
The tip lightly “taps” on the sample surface during scanning, contacting the surface at the bottom of each oscillation. 
Tip artefacts
Artefacts result from the tip either becoming contaminated by material on the sample surface or from wear due to scanning. 
Virtual SPM - Nanotubes