Question

Atomic Force Microscopy monitors:

• A. Current between the surface and the probe
• B. Force between the surface and the probe
• C. Electromagnetic radiation between the surface and the probe
• D. distance between the surface and the probe

Hint:

The names of the two main scanning probe techniques tell you what they measure:

Scanning \textbf{Tunneling} Microscopy \(\rightarrow\) measures tunneling \textbf{current}.
Atomic \textbf{Force} Microscopy \(\rightarrow\) measures atomic \textbf{force}.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
This question asks for the fundamental physical quantity that is measured in Atomic Force Microscopy (AFM) to generate an image of a surface.
Step 2: Detailed Explanation:
The name "Atomic Force Microscopy" itself reveals the working principle. The instrument uses a micro-fabricated cantilever with a sharp tip at its end. This tip is brought very close to the sample surface.
At this close proximity, interatomic forces (such as van der Waals forces, electrostatic forces, magnetic forces, etc.) act between the atoms on the tip and the atoms on the surface. These forces cause the flexible cantilever to bend or deflect.
An AFM system monitors this deflection, typically by reflecting a laser beam off the back of the cantilever onto a position-sensitive photodetector. The amount of deflection is directly related to the strength of the tip-sample force via Hooke's Law for the cantilever.
By scanning the tip across the surface and recording the deflection (or the height adjustment needed to keep the deflection constant), a map of the surface topography is created. Therefore, the AFM directly monitors the force between the surface and the probe.
Step 3: Final Answer:
Atomic Force Microscopy generates images by monitoring the forces between a sharp probe and the atoms on a sample surface.