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Glossary terms about Sample

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


36 pages mention Sample

AFM calibration methods
 
AFM imaging modes
AFM can operate in three modes according to how the AFM probe moves: Contact mode is also called static mode, and is where the probe does not oscillate and is always in very close contact with the sample surface. 
AFM imaging of surfaces
 
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
 
AFM probe modification
 
AFM: Background information
The Atomic Force Microscope (AFM) operates by scanning an AFM probe across a sample surface. 
Cantilever tuning - only for tapping and non-contact modes
 
Contact and tapping modes
This means that the user gets the greatest sensitivity to measure the topography of the sample
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. 
Discontinuous
 
Feedback
 
Floating control
 
Force distance spectroscopy
Journal Link... Creasey, R., Sharma, S., et al. Detecting Protein Aggregates on Untreated Human Tissue samples by Atomic Force Microscopy Recognition Imaging. 
Gains
The higher the values, the faster the AFM will react to changes in the topography in the sample
How is the Data Displayed?
Most Scanning Probe experiments produce data as a function of the sample's x and y position. 
Image artefacts
This allows such probes to access parts of a sample ordinary AFM tips cannot. 
Image Scanning and feedback parameter optimisation - scan rate
Scan rate: This parameter obviously controls the speed at which the tip moves over the sample surface. 
Integral control
 
Introduction
Electron microscopes create magnified images of samples by focusing an electron beam using magnetic fields produced by electromagnetic lenses composed of wire coils. 
Measuring forces in the tip-sample space
In addition to imaging the surface of samples, another major application of AFM is force spectroscopy. 
Near-field scanning optical microscope (NSOM/SNOM)
Light is passed through the waveguide onto the sample and resulting light is detected via various means or alternatively the sample is optical excited and the resulting light is detected using the waveguide. 
Non-contact mode
Non-contact mode prevents tip and sample degradation from contact between the two, and is therefore good for soft samples such as biological specimens and thin organic films. 
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
 
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)
STM is the oldest of the scanning probe microscopes and involves bringing an atomically sharp tip within a couple of nanometres of the sample
Set point - Tapping mode
In this mode of operation, set-point refers to the amplitude of oscillation of the cantilever at which the tip taps the sample surface. 
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
For sample scanning systems sample size is also typically restricted to a maximum area of 1x1 cm and with a maximum sample thickness of approximately 3 mm. 
Tapping mode
Tapping Mode AFM operates by scanning a tip attached to the end of an oscillating cantilever across the sample surface. 
Tip artefacts
Artefacts result from the tip either becoming contaminated by material on the sample surface or from wear due to scanning. 
Virtual Scanning probe microscopy
Please select which sample you would like to view under the scanning probe microscope. 
Virtual SPM - Calibration grid
 
Virtual SPM - Nanotubes