TRANSMISSION ELECTRON MICROSCOPY
Transmission electron microscopy (TEM) is the microscopy technique where a beam of electrons penetrates through the sample to produce a magnified image.
Before 1931 when Max Knoll and Ernst Ruska demonstrated the first working TEM microscope, light microscopy was the only method scientists and researchers were able to magnify their samples with. Light microscopy could only take magnifications as far as the micro scale due to the limitation of the wavelength of light. The need for a more powerful microscope that could image at much higher magnification levels and produce clean and clear results was obvious. The first commercial TEM microscope was developed in 1939, and since then continuous improvements to TEM’s has consistently pushed the boundaries of magnification power and image contrast.
With TEM, electrons are scattered from their path by interaction with the atoms of the sample. This interaction is what provides the image contrast as some electrons pass through the sample and others are bounced away. From that point, the image is focused and magnified using a combination of apertures and lenses onto an imaging device. Transmission electron microscopes have become a critical analytical tool in the materials and life sciences as magnification levels now obtained are at the nano-level and beyond, allowing new and important technologies to pave the way in the 21st century.
Conventional TEM Microscopes
A conventional TEM microscope is a very large and complex piece of equipment that usually requires a specially trained technician to operate and maintain the tool. These microscopes have operating voltages that normally range from 80Kv (for the imaging of organic materials), to 300Kv (for the imaging of organic and solid materials. There are even some that operate at 1000 Kv where imaging is possible at the atomic level. These instruments can cost millions of dollars. Conventional TEMs require a substantial amount of space for their installation as well as specialized facilities such as anti-vibration stabilizing platforms, special power connections, and cooling chambers for the electromagnetic coils.
How LVEM does TEM
The LVEM5 and LVEM25 are unique microscopes, in that they employ low voltage electron sources between 5 and 25 kV. These can produce higher contrast images due to a higher degree of electron scatter when interacting with the sample.
Benefits of improved contrast include:
- Lower threshold for density differences
- The ability to visualize samples that cannot be resolved by high voltage methods without the use of heavy metal stains
- The avoidance of artifacts when imaging the sample which are brought on by heavy metal stains
Other unique features exclusive to the LVEM TEM microscopes are the facts that they don’t require any specialized technician to operate them, have very basic maintenance requirements and don’t require any special facilities for their installation. The LVEM5 comes in a convenient benchtop format and the LVEM25 is just a little larger and comes on its own dedicated rolling platform. These microscopes are much more cost-effective options when compared to conventional TEM’s. For more details, please visit the product details pages for the LVEM5 or the LVEM25.
LVEM Samples and Applications for TEM
Typical samples for TEM analysis are broken down into 2 basic categories; ultrathin sections of bulk materials, or nano-sized particles or filaments deposited onto a support film
|EXAMPLES OF TEM SAMPLES|
|Silver nanoparticles||Gold nanoparticles|
|Virus and Phages||Liposomes|
|EXAMPLES OF TEM APPLICATIONS|
|Filament morphology||Finding changes in tissue|
|Size distribution||Study of ultrastructure|
|Particle morphology||The understanding of the interface of biomaterials and tissue|
|Crystal Structure||Location and organization of organelles within cells|
|Phase behaviour||Virus detection|
|Phase composition||Location of actin filaments in the cytoskeleton|
LVEM Sample Prep for TEM
Bulk materials like polymers or biological thin sections are generally required to be thin-sectioned for TEM analysis. The LVEM25 can work with thin sectioned materials prepared in the same way as that of a conventional TEM, at around 100nm. For best results with the LVEM5, thin sections need to be in the range of 50 nm or thinner. As is the case with both LVEM units, the staining of samples is not required but can still be accommodated.
Particulate materials such as nanoparticles, nanotubes, viruses and DNA can easily be deposited at the appropriate concentration onto a TEM grid with a carbon support. For more details, please visit our page on sample preparation.
Visit our photo gallery for a better look at what transmission electron microscopy within the LVEM5 microscope can do for you.