Learn More About TEM

Learn More About TEM

Scientists report the size of a SARS-CoV-2 particle to be between 50-140 nm (https://www.news-medical.net/health/The-Size-of-SARS-CoV-2-Compared-to-Other-Things.aspx). 

New microprocessor technology in devices from companies like Apple, Intel, and AMD produces chips with features as small as 5-10 nm. Shale rock that is mined for petroleum and natural gas contains a pore structure that can be as small as 5 nm.  Wow- that’s very, very small!

Virologists, Electrical Engineers, Petroleum Engineers and Geologists; these are all very different professions.  The one thing they have in common is the need to study things that are extremely small, nano-sized particles and materials.  It’s hard to imagine because this is smaller than anything we can see with only our eyes. As a quick refresher, a nanometer (nm) is one-billionth of a meter.  For reference a single human hair is ~50,000 nanometers in diameter.  Scientists and engineers who need to study nano-sized particles or structures require a unique microscope called a Transmission Electron Microscope, or TEM for short.

Before we go any further, we should take a step back and discuss a few basics of microscopy.  When we look through the eyepiece of a microscope, the magnified image we see is created by a series of lenses, each behaving like a magnifying glass.  Various lenses give us higher and higher magnification.  How well that magnified image can be resolved is dependent on the wavelength of the source used.  In a standard light microscope, the wavelength of the light is about 500 nm.  Thus, we can resolve objects that are about 250 nm or more apart.  Anything smaller than this is too fuzzy, and the objects are blurred together.  Secondly, in a light microscope the light reflects from the sample and is projected to our eyes or perhaps to a detector that generates a digital image.

To see smaller objects with clarity we need to use a source with a wavelength less than that of visible light.  This is where electrons come in! The benefit of the electron source is that the wavelength of the electrons in the beam is only a few picometers, 1 picometer = 1000 nanometers. With the electron beam as the source of the object being viewed, it can be magnified even more and the details of a material or cell that are only 0.5 or 0.25 nanometer can be seen clearly.  

As the name indicates, in a TEM the electrons are transmitted through the sample.  Fundamentally, the TEM is analogous to a slide projector.  In a slide projector, a light bulb is used as the “source.”  The beam of light is collimated and passed through a photographic slide that is transparent. Then the beam is focused and projected onto a screen.  If you grew up in the 1970s this is how you captured all your family memories and replayed them.  In a TEM the electron source replaces the light bulb, the beam of electrons is focused with a series of lenses and passed through a very thin (100 nm or less) sample of the material being studied. The electrons change a little as they pass through the sample and thus when they are focused and projected onto a special screen, they produce a picture of the object.  Below is an example of a TEM image of carbon nanotubes.  In the image you can see the details of the sub-nanometer layers that make up multi-walled tubes!

Scientists at Cerium Laboratories use TEM daily to investigate a variety of samples for our customers.  We evaluate the internal structures of microprocessors that operate your cell phone, laptop and car.  We evaluate devices used for generating solar power.  We look at geological formations to help scientists better understand where natural gas and oil deposits are located.  

We analyze the finest details that are so minute but are so critical! We have a team with extensive experience in material characterization and research and development programs, including TEM but certainly not limited to it. If you’re ready to find out exactly what we can do for you, we want to hear from you!