Question

4. For an atomic force microscope (AFM). each atom of the probe tip participates in imaging. The strongest van der Waals attractive force occurs between the shaded atoms 1-3 and the surface atoms. which will see the sample as a periodic lattice. But because the atoms of the tip are in different height and lateral positions, the lattice that each atom sees is different in magnitude and shifted from the lattice seen by its neighbors. Sketch qualitatively the van der Waals forces between atoms 1-3 and the surface in Fig. 2. then stun them up and analyze how this will influence the resolution of an AFM.

Answer 1

Repulsive +A/r12 Attractive -Bir6

AFM instrument works based on attractive and repulsive forces, which can be understood well by above potental energy level diagram. There are tow atoms, one is from tip and another atom from surface of the sample under investgation. When tip moves towards the surface of the sample, there will attrcive forces between two atoms and repulsive forces comes to play when atoms moves close further. we can understand this easily from from above digram. As asked in the question, among atoms 1, 2, and 3. atom 1 will experiance more attarcive and repulsive forces when tip moves to the specimen. The resolution mainly depends on interaction of atoms and difflection laser beam.