In my previous notes, I have already discussed Transmission Electron Microscope and Scanning Electron Microscope, their working principle, parts, definition, application, advantages, disadvantages, and light path. You can check them out.
20 Difference Between Transmission and Scanning Electron Microscope
| Topic | Transmission Electron Microscope | Scanning Electron Microscope |
|---|---|---|
| 3D/2D Image | 2D projection image of the inner structure | 3D image of surface |
| Type of electrons | Transmitted electrons | Scattered, scanning electrons |
| Max. FOV | Limited | Large |
| Principle | Based on transmitted electrons or produces images by detecting primary electrons transmitted from the sample | Based on scattered electrons or produces images by detecting secondary electrons which are emitted from the surface due to excitation by the primary electron beam |
| Specimen Preparation | Complex processes. | Easy processes |
| Specimen thickness | Typically <150 nm | Any |
| Operation | Laborious sample preparation, trained users required | Little or no sample preparation, easy to use |
| Maximum magnification | More than 50 million times | Up to ~1–2 million times |
| Depth of field | Moderate | High |
| High tension | ~60–300 kV | ~1–30 kV |
| Optimal spatial resolution | <50 pm | ~0.5 nm |
| Image formation | Direct imaging on a fluorescent screen or PC screen with CCD | Electrons are captured and counted by detectors, image on PC screen |
| Specimen mounting | Thin films on copper grids | Aluminum stubs |
| Application | Used to study the ultra structure of the cell and its components. It can see objects as small as a protein molecule or even at nano level. Provides details about internal composition of cells or any suitable material under study | Used to produce excellent images of the surfaces of cells and small organisms. Excellent for studying surface morphology of the organisms, cells or any suitable material under study |
| Imaging | The electron beam passes through the sample and creates an image of the specimen | Electron beam scans over the surface of the sample and create an image of the specimen. |
| Specimen Fixation | Specimen fixation is completed by two methods Chemical fixation of specimen and Cryofixation fixation of the specimen. | Specimen fixation is completed by ALDEHYDES and OSMIUM TETROXIDE |
| Coating of specimen | Not required. | the specimen is coated with a conductive material to prevent the charge buildup on specimen surface. |
| Polishing | This is done with the Ultrafine abrasives, to give the sample a mirror-like finish. | Not Required. |
| Produce portable digital data | No. | Produces |
| Time | Long process as compared to SEM | Require less time as compared to TEM |
Reference
- https://www.majordifferences.com/2016/08/difference-between-sem-and-tem.html
- https://www.thermofisher.com/in/en/home/materials-science/learning-center/applications/sem-tem-difference.html
- https://microbiologynote.com/scanning-electron-microscope-definition/
- https://microbiologynote.com/transmission-electron-microscope/
