Structural devices
Structural devices

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

Structural devices

3.5.1 Contact mode

Contact mode produces images with the highest resolution. This is because when the probe tip is as close as it can be to the surface, the influence of atoms other than the one directly under the probe tip is relatively small. This is a simple geometrical effect – if the tip were withdrawn a large distance from the surface, a large number of atoms would be at a very similar distance from the tip, and therefore would have a similar contribution to the overall force. In contact mode, the repulsive force between tip and sample is sufficient to deflect the cantilever. How much the cantilever is allowed to deflect will determine the force it exerts on the sample, in proportion to its flexural stiffness. Cantilevers of low stiffness are desirable here, because it is easy to ensure that excessive force is not applied to the surface being scanned, since a large deflection results in a small change in the applied force.


Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus