Atomic Force Microscopy
• AFM introduction
• AFM machinery
• Cantilevers
• Contact models / Van der Waals forces
• Contact mode imaging
• Lateral forces
• Force modulation
Original Idea of AFM
One year later: Atomic Resolution
Modern AFM• Common displacement detection methods
– Beam bounce
– Interferometric
– Piezoresistive
• Generally characterized by minimum detectable
displacement per squareroot Hz (mechanical
displacement noise level)
Also readAlso read : : http://www.physikinstrumente.com/en/products/piezo_tutorial.phphttp://www.physikinstrumente.com/en/products/piezo_tutorial.php
A quick comparison
All methods have applications depending on their strengths and weaknesses
PZR
Modern cantilevers• Generally micromachined out of silicon and silicon nitride
Copyrighted material, used for educational purposes
Tip-sample Contact • Hertzian contact theory is a good starting point
Elasticity of materials
Contact Mode Imaging
Contact mode imaging
• Contact force
– Think about contact area and pressure
• Modifications to tip and sample
• Easier (no harmonic oscillator response to
deal with) and higher stability
• Subject to DC drifts
