Lecture

SEM Basics: Introduction to Electron Microscopy

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In course

MSE-636: Organic semiconductors

Description

This lecture covers the basics of scanning electron microscopy (SEM), including the setup, electron sources, lenses, vacuum system, and detection system. It explains the electron-matter interactions, resolution, and why fast electrons are essential. The lecture also delves into SEM techniques, such as chemical analysis and Monte Carlo simulations, and discusses the consequences of using electrons, the vacuum system components, and the various types of lenses used in SEM. It further explores electron optics, aberrations, and detectors, emphasizing the importance of understanding trade-offs in SEM imaging.

Instructor

Frank Nüesch

Teaching & PhD PhD Students Elodie Didier, Ceren Mitmit, João Pedro Ferreira Assunção, Vahid Charkhesht Past EPFL PhD Students Hui Zhang, Simon Johannes Dünki, Yee Song Ko, Lei Wang, Sandra Christina Jenatsch, Nicolas Alexandre Serge Leclaire, Donatas Gesevicius, Surendra Babu Anantharaman, Markus Regnat, Philip Horst Caspari, Patrik Schürch, David Reber, Karen Verena Strassel, Sina Abdolhosseinzadeh, Matthias Diethelm, Francis Owusu, Camilla Arietta Vael-Garn, Yeerlan Adeli, Wei-Hsu Hu, Cansu Zeytun Kara

Official source

Ontological neighbourhood

Physics

Optics: Geometrical optics

Industrial and production engineering

Manufacturing engineering: Electron-beam technology

Related concepts (32)

Electron microscope

An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light, electron microscopes have a higher resolution of about 0.1 nm, which compares to about 200 nm for light microscopes.

Transmission electron microscopy

Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a grid. An image is formed from the interaction of the electrons with the sample as the beam is transmitted through the specimen. The image is then magnified and focused onto an imaging device, such as a fluorescent screen, a layer of photographic film, or a sensor such as a scintillator attached to a charge-coupled device.

Scanning electron microscope

A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image.

Lens

A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (elements), usually arranged along a common axis. Lenses are made from materials such as glass or plastic and are ground, polished, or molded to the required shape. A lens can focus light to form an , unlike a prism, which refracts light without focusing.

Cryogenic electron microscopy

Cryogenic electron microscopy (cryo-EM) is a cryomicroscopy technique applied on samples cooled to cryogenic temperatures. For biological specimens, the structure is preserved by embedding in an environment of vitreous ice. An aqueous sample solution is applied to a grid-mesh and plunge-frozen in liquid ethane or a mixture of liquid ethane and propane. While development of the technique began in the 1970s, recent advances in detector technology and software algorithms have allowed for the determination of biomolecular structures at near-atomic resolution.

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