The Electron Microscope

Question 1

How do electron microscopes work?

Answer 1

Electron microscopes work by focusing a beam of electrons onto a sample using electromagnets.

Question 2

What is the key difference between Transmission Electron Microscopes and Scanning Electron Microscopes?

Answer 2

1. In TEM, specimens must be extremely thin, resulting in a 2D image, whereas in SEM, specimens can be thicker, producing a 3D image.

Question 3

What are limitations of TEM and SEM?

Answer 3

TEM
-Whole system must be in a vacuum, therefore all sample must be dead.
-A complex staining process is required, and even then the image is not in colour.
-The specimen must be extremely thin.

SEM
-All limitations from TEM apply apart from samples needing to be extremely thin.
-Has a lower resolving power than a TEM.