I want to know the difference in the application of Scanning electron microscopy and Transmission electron microscopy. I intend using either of these applications to view plant matrix for structural changes due to accumulation of metals and nano particle after exposure. Could someone give a detailed enlightenment on this, pls
Thank you Mostafa and Mohamed. i really appreciate this brief and concise information. Thanks alot.
SEM actually works to evaluate the surface topography by help of electromgnetic zoom lenses which raster the surface. The method used in SEM is based on scattered electrons while TEM is based on transmitted electrons.
SEM focuses on the sample’s surface and its composition. On the other hand, TEM seeks to see inside the material or beyond the surface.
In terms of magnification and resolution, TEM has an advantage compared to SEM. TEM has up to a 50 million magnification level while SEM only offers 2 million as a maximum level of magnification. The resolution of TEM is 0.5 angstroms while SEM has 0.4 nanometers. However, SEM images have a better depth of field compared to TEM produced images.
. The sample in TEM is cut thinner in contrast to a SEM sample. TEM sample preparation required more skill than SEM sample preparation.
18/09/2014
SEM is an evaluation of surface fine structure of cells and TEM an evaluation of internal fine structure of cells. This is a short summary, but for the rest I agree with all the above comments. The term ultrastructure is also used for fine structure.
Kind regards,
Johan (JT) Nel.
@ Patra and Johan, thanks for this wonderful explanation. I really appreciate your comments.
There's even more: If you can afford a crossbeam microscope with focused ion beam AND cryo function, you may freeze your bulk sample, insert it into your microscope and study it's surface topography and surface element composition with the SEM mode. In addition, you may use the FIB to cut into your sample and perform the same analysis with the crossbeam of the cut, which may provide information about the metal distribution across the entire structure. And finally, you can use a micromanipulator in combination with the FIB to cut out a very thin slice of your sample and transfer it to an STEM holder (if available) and obtain highly resolved 2D images. Best of both worlds; expensive, though.
@Zhou, Please what is the difference between the discussed (SEM and TEM) and ESEM you just mentioned? Can you give details about this techniques.
SEM and TEM are performed in high vacuum. As far as I know, ESEM works with much higher pressure and in gas atmosphere. The gas itself is utilized for signal magnification (collisions of secondary ions from the sample with gas molecules). E stands for environmental.
SEM gives you the morphology of the sample being studied while TEM is more precise in giving the particle size.
Attached comprehensive comparative between SEM and TEM might give you a clear idea.
TEM and SEM are the electron microscope techniques used for the study of morphology and particle size analysis of your material. In both of them TEM is more precise because advantage over SEM that one may know particle size and morphology too..........
TEM using thin sections, then destroys the sample and obtain 2D images at very high resolution.
SEM uses the entire sample, then you can watch 3D images, and "fly over" the sample as a helicopter.
Hi,
Electron microscope follows the same ideas of optical microscope, but uses electrons instead of light;“Lens” here are not the optical materials (like glass), but electrical field.
A Scanning Electron Microscope uses a beam of electrons to scan the surface of an object to create an image detailing the topography and composition of the object’s surface.
A Transmission Electron Microscope is used to magnify objects. It aims a beam of electrons onto the object to form a magnified image called a micrograph.
In SEM an electron beam is focused into a small probe and is rastered across the surface of a specimen.Several interactions with the sample that result in the emission of electrons or photons occur as the electrons penetrate the surface.These emitted particles can be collected with the appropriate detector to yield valuable information about the material.The most immediate result of observation in the scanning electron microscope is that it displays the shape of the sample.The resolution is determined by beam diameter.
In transmission electron microscopy (TEM), a beam of highly focused electrons are directed toward a thinned sample (
Both TEM and SEM characterization technique uses electron beam. In case of SEM the electron beam raster on the surface and provide topographical as well as morphology of the sample.
Whereas in TEM study the electron transmit through the central thinned area of the sample (in case of solid sample) and provide you the particle size as well as diffraction pattern (selected area diffraction). After you index (identify the plane of diffraction) the pattern correlate with the elemental mapping and energy dispersive spectroscopy (EDS) attached with the TEM equipment.
However more attention is to be paid during preparation of sample before TEM study for more precise results.
EDS attachment is present in both SEM and TEM equipment. However TEM provides you more reliable data if your interest is to identify the elemental composition.
Thanking you.
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