what is the difference between tem tem (transmission electron microscope) and sem(scanning electron microscope

Question

atleast 15 differences

Answer 1

A Scanning Electron Microscope (SEM) is used to look at the surface of solid objects. The object you are looking at must be coated with an electron dense material - usually a very fine coating of gold. Electrons are fired at the object, reflecting off the surface and are then collected to form a 3-D image. The object itself is mounted on a small stage that can be rotated around so that you can look at different side and zoom in.

A Transmission Electron Microscope is used to look at the internal structure of material. This is done by 'staining' the material with an electron dense substance (often Osmium) and then the material is sliced up very thinly ( a few nanometres). Electrons are fired at the slice (which is mounted on a very fine copper grid) - some go through and some do not. The ones that get through form an image on a screen.

Answer 2

Scanning EM usually does not have enough resolution to see individual proteins. TEM can get a lot better resolution and the 1mm thick glass would not be a problem, in fact thats how you usually mount images... How large your protein is might be an issue, I believe it needs to be at least 40 KD to be visible. If you are just trying to test for the presence of protein there are a lot easier less expensive ways, what exactly are you trying to do?

Answer 3

In case of tem image is formed by transmission of electrons,whereas in sem image is formed through striking on to specimen.
In tem very thin sections are used, in sem thin sections are not needed.
In tem magnetic lens are used , in sem these are not used.
In tem copper grid is used , in sem this is not used.

Answer 4

Tem uses the wave nature of electrons and sem uses their particle nature.