1.1 - Introduction to transmission electron microscopy (TEM)

Summary

In this introductory course on Transmission Electron Microscopy (TEM), Professor Calvin Shear from Texas A&M University offers a comprehensive overview of TEM's principles and applications. He shares his academic background and research experience using TEM in various studies, including materials characterization and phase transformations. The course covers five sections: basics, diffraction, imaging, spectroscopy, and related TEM techniques. It utilizes several key textbooks and resources, emphasizing the structural and chemical information TEM provides. The course also highlights advanced TEM techniques like aberration correction and scanning transmission electron microscopy (STEM).

Takeaways

• 🤠 The course is an introduction to Transmission Electron Microscopy (TEM), taught by Calvin Shear, an assistant professor in the Department of Material Science and Engineering at Texas A&M University.
• 🎓 Calvin Shear has a diverse academic background, with undergraduate studies in biomedical engineering and finance at the University of Sydney, and a PhD in mechanical engineering focusing on high-strength low-alloy steel.
• 🔬 TEM and Atom Probe were key tools in his research during his PhD to study solute clusters, and post-PhD, he worked at Johns Hopkins University, using TEM to study deformation mechanisms in boron carbide and magnesium.
• 🧑‍🏫 The course will cover a wide range of topics, including electron scattering, instrumentation, sample preparation, diffraction, imaging, spectroscopy, and related TEM techniques.
• 📚 The main textbook for the course is 'Transmission Electron Microscopy' by Williams and Carter, supported by other resources like 'Microstructural Characterization of Materials' and 'Aberration-Corrected Imaging'.
• 🖼️ Five main sections of the course include basics, diffraction, imaging, spectroscopy, and TEM-related techniques, with detailed discussions on each topic.
• 💡 In the basics, the course will explore electron scattering, electron sources, and lenses, as well as sample preparation methods like electro-polishing and lift-out for specific samples.
• 📐 The diffraction section covers parallel beam diffraction, Kikuchi diffraction, and convergent beam electron diffraction, explaining how each provides different visual patterns (spots, lines, disks).
• 🔍 Imaging will delve into three types of contrast (mass-thickness, diffraction, and phase contrast) to analyze different materials and samples at atomic resolution.
• 🌈 The spectroscopy section introduces EDS and EELS techniques, enabling students to gather both chemical and bonding information about materials, particularly when combined with scanning TEM and aberration correction.

Q & A

What is the main focus of this Transmission Electron Microscopy (TEM) class?

The main focus of this class is to provide an overview of Transmission Electron Microscopy (TEM) and its applications in material science.

Who is the instructor of the class, and what is his academic background?

The instructor is Calvin Shear, an assistant professor in the Department of Material Science and Engineering at Texas A&M University. He has a background in biomedical engineering and finance from the University of Sydney and a PhD in mechanical engineering.

What technique is emphasized in this course that is specific to Texas A&M University?

The course emphasizes the use of a special TEM technique called precession electron diffraction, which is used to study the formation and phase transformations in materials.

Which textbook is primarily used for this course, and what is its significance?

The textbook used is 'Transmission Electron Microscopy' by Williams and Carter, often referred to as the 'Bible' for TEM due to its comprehensive coverage of the subject.

What are the five main sections of the TEM course as outlined by the instructor?

The five main sections of the course are basics, diffraction, imaging, spectroscopy, and TEM-related techniques.

What are the three types of contrast discussed in the imaging section of the course?

The three types of contrast discussed are mass-thickness contrast, diffraction contrast, and phase contrast. These contrasts help in imaging biological samples, crystal defects, and atomic structures, respectively.

What are the two spectroscopy techniques covered in the course, and what information do they provide?

The two spectroscopy techniques are Energy Dispersive X-ray Spectroscopy (EDS) and Electron Energy Loss Spectroscopy (EELS). EDS provides chemical information, while EELS offers both chemical and chemical bonding information.

How does the instructor describe the impact of aberration correction in TEM imaging?

The instructor explains that aberration correction in TEM significantly improves image quality. He shows an example where an aberration-corrected image reveals more detailed atomic structures compared to a non-corrected image.

What is the significance of combining EDS and EELS with STEM in the context of this course?

Combining EDS and EELS with Scanning Transmission Electron Microscopy (STEM) allows for the chemical analysis of individual atomic columns, providing highly detailed structural and chemical information.

What is the expected outcome for students by the end of this TEM course?

By the end of the course, students are expected to have a good understanding of how TEM works and how it can be applied to research in material science.