The key difference between SEM and TEM is that SEM creates an image by detecting reflected electrons, whereas TEM creates an image by detecting transmitted electrons.
SEM and TEM are analytical instruments that we use in electron microscopy to get an image of a tiny object using a beam of electrons.
CONTENTS
1. Overview and Key Difference
2. What is SEM
3. What is TEM
4. Side by Side Comparison –SEM vs TEM in Tabular Form
5. Summary
What is SEM?
SEM stands for scanning electron microscope. It creates images of samples by scanning the surface of the sample. It uses a beam of electrons that is focused towards the sample. These electrons interact with the atoms on the surface of the sample, producing different signals to express the topography of the surface. A detector detects these signals to create an image. The detector we use here is Everhart-Thornley detector.
Figure 01: Sample Chamber of SEM
The image given by this technique is three dimensional, and it can go to about a maximum of 2 million magnifications. Moreover, the resolution is about 0.4 nanometers.
What is TEM?
TEM stands for transmission electron microscope. This microscope transmits a beam of electrons through a sample. Thus, this creates an image of the internal structure of the sample. Furthermore, this image is created due to the interaction between electrons and the atoms of the sample. Moreover, we can get the image on a fluorescent screen or a photographic film.
Figure 2: An Image Obtained from TEM
When considering the resolution, this instrument can give about 0.5-angstrom resolution. Furthermore, it can magnify a specimen to about 50 million times than the original. However, the image given by TEM is two dimensional.
What is the Difference Between SEM and TEM?
SEM stands for scanning electron microscope while TEM stands for transmission electron microscope. The key difference between SEM and TEM is that SEM creates an image by detecting reflected electrons, whereas TEM creates an image by detecting transmitted electrons. SEM analyzes the surface of a sample while TEM analyses the internal structure. Another difference between SEM and TEM is their resolution The resolution of the SEM technique is about 0.4 nanometers whereas TEM gives about 0.5 angstroms.
Summary – SEM vs TEM
SEM stands for scanning electron microscope while TEM stands for transmission electron microscope. The key difference between SEM and TEM is that SEM creates an image by detecting reflected electrons, whereas TEM creates an image by detecting transmitted electrons.
Reference:
1. Zhao, Shiye, et al. “Limitations for Microplastic Quantification in the Ocean and Recommendations for Improvement and Standardization.” Microplastic Contamination in Aquatic Environments, 2018, pp. 27–49., doi:10.1016/b978-0-12-813747-5.00002-3.
Image Courtesy:
1. “SEM chamber1” (CC BY-SA 2.5) via Commons Wikimedia
2. “Polio EM PHIL 1875 lores” By CDC/ Dr. Fred Murphy, Sylvia Whitfield – from the Centers for Disease Control and Prevention’s Public Health Image Library (PHIL), (Public Domain) via Commons Wikimedia