Monthly Archives: October 2016

Angstrom Advanced Atomic Force Microscopes: Modes

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Years of innovation and design have lead to the Angstrom Advanced Inc. AFMs leading the industry in high-precision, low noise, low drift and measurements, which deliver artifact-free images in minutes. Functionality, usability and precise results combined with large sample platforms which save time and hassle

Non-Contact AFM Non-Contact AFM oscillates the cantilever at a constant frequency with an amplitude around 10 nm. The height of the surface can be found by measuring the output of the control loop which keeps the frequency constant. Non-contact Atomic Force Microscopes scan much quicker than contact microscopes because the tip does not fatigue. Non-contact AFM is also useful for measuring flexible samples. Contact AFM can scratch and alter the surface of softer samples. The contact method can penetrate through liquids while non-contact will read surface liquids as the sample surface.
Tapping Method Tapping Atomic Force Microscopes have large oscillations in the tip (100 to 200 nm) which are damped by Van der Waals and dipole forces from the surface of the sample. This method is more gentle than the traditional contact method. The tapping method can also measure through liquid surfaces when used properly.
Conductive AFM Option (C-AFM) CAFM measures both the surface topography and the conductivity of a samples. Voltage is applied to the tip and the current through the tip and sample is measured. It is used for semiconducting, low and medium conducting materials.
Contact Mode The tip is always in contact with the sample surface in contact AFM. The deflection of the tip is measured and held constant by a feedback loop. The stiffness of the cantilever must be low enough to prevent the tip from altering the surface of the sample.
Scanning Tunneling Microscope Angstrom Advanced Scanning Tunneling Microscopes (STM) have a tip which is actuated in the vertical direction by a piezoelectric crystal. The readings from a scanning tunneling microscope are limited by the sharpness of the tip. STM is a different method of getting very similar results to AFM. It maintains a constant distance from the sample through a feedback controller to measure the surface of the sample.