Question

Please briefly answer all the questions below, and writing those clearer and tidier (It is best to use typing)

This is a problem related to the atomic force microscopy (AFM).

1. Please describe the difference in operation among the three common imaging modes, ie. Contact, non-contact, and intermittent, of the atomic force microscopy, and the advantage and disadvantage of these modes.
2. Describe how the positon-sensitive diode is used in AFM?

Answer 1

b.

A laser beam is used to detect cantilever deflections towards or away from the surface. By reflecting an incident beam off the flat top of the cantilever, any cantilever deflection will cause slight changes in the direction of the reflected beam. A position-sensitive photo diode (PSPD) can be used to track these changes. Thus, if an AFM tip passes over a raised surface feature, the resulting cantilever deflection (and the subsequent change in direction of reflected beam) is recorded by the PSPD.