20.309:AFM LAB MANUAL

Objectives and Learning Goals

• Learn the function of the 20.309 AFM and the relationships between its components.
• Understand how to extract quantitative information from this tool.
• Use the AFM to take images, probe sample stiffness, and estimate the value of a fundamental physical constant.
• Analyze the sources of uncertainty and noise in the system that limit the accuracy of measurements.

Roadmap and Milestones

The AFM will be the basis of three weeks' worth of experiments, and the roadmap below is subdivided into weeks to help you gauge your progress.

Week 1

1. Learn the signal paths and connections of the system.
2. Practice aligning the AFM optics.
3. Learn how to calibrate the AFM to extract useful physical data.
4. Measure the vibrational noise floor in the AFM system.
5. Set up and prepare the AFM for imaging.

Week 2

1. Image several different samples with the AFM and measure the physical dimensions of imaged features (Experimment 1).
2. Use the AFM to measure the elastic modulus and surface adhesion force of several different samples (Experiment 2).

Week 3

1. Use your knowledge of the AFM system and associated instrumentation to record the vibrational noise spectrum of a cantilever probe (Experiment 3).
2. Calculate the value of Boltzmann's Constant Kbfrom the vibrational spectrum.