Starter for TEM

ChemSci Pick of the Week

Today’s ChemSci Pick of the Week begins to look at how transmission electron microscopy works – and how to improve its capability.

Transmission electron microscopy (TEM) is a way of imaging extremely small objects, and can show details on the scale of individual atoms. It’s used in cancer research and materials science, as well as nanotechnology research.

It works by transmitting a beam of electrons – which passes through the sample being examined to form an image. Unfortunately this technique can cause damage to the molecules in question, via a process known as radiolysis.

Lin-Wang Wang, Shiyou Chen and Zenghua Cai, an international team from universities in China and the US, have set out to study how this damage occurs.

Under the electron beam, a molecule in the sample can undergo ionisation – it could lose one of its electrons. "Since the electron is what makes the chemical bond, which binds the atoms together to form a material," explains Lin-Wang Weng, "it can weaken its bond, and eventually break down the molecule."

The exact mechanism by which this process occurs is, however, poorly understood. If we can understand the mechanism, we can start to understand how to avoid the breakdown of molecules under these conditions. Not only will this help us to use TEM imaging without damaging the sample, but it will also shine a light on, for example, the mechanism by which cancer can be caused by radiation.

"Our research unravelled the mechanism behind the radiolysis damage of molecules under the illumination of an electron beam", says Shiyou Chen. "This could be helpful to find the way for reducing the radiolysis damage to molecules, such as alcohol, biomedical molecules and so on."

Lin-Wang Wang explains the implications of this work:

"Such understanding can help us to control electron beam damage, thus allowing the use of TEM to observe many more physical phenomena. TEM is one of the main tools we have to directly observe the microscopic world at atomic level. Improving its capability will significantly advance our scientific power, and help to design new materials and techniques – from batteries to water splitting."

This article is free to read in our open access, flagship journal Chemical Science: Zeng-Hua Cai, Shiyou Chen and Lin-Wang Wang, Chem. Sci., 2019, Advance Article. DOI: 10.1039/C9SC04100A. You can access our 2019 ChemSci Picks in this article collection.