Introduction to Electron Microscopy-Scanning Electron Microscopy. This course is a practical introduction to techniques of electron microscopy and to the scanning electron microscope. Use of the microscope, introduction to darkroom techniques and digital image processing along with preparation of samples for observation, and special projects.
- Three generic types of microscopes, their advantages and disadvantages. Why use electrons to make pictures.
- The SEM - fundamental operation. The meaning of magnification.
- Basic SEM hardware - the electron gun, lenses, and apertures. Why is a vacuum required? Notes on vacuum pumps, seals, and guages.
- Electron-solid interactions, backscattered and secondary electron signals.
The idea of interaction volume and electron range.
- Secondary electron imaging. The Everhart Thornley SE detector. Secondary electron topography - interpreting the image. Other SE imaging modes.
- Backscattered electron imaging. Types of BSE detectors. Atomic number (Z) contrast, topographic imaging. Other BSE imaging modes. Labeling.
- Signal to noise in the SEM. Information, noise, and contrast. The threshold current limit Signal processing in SEM, Blacklevel, peak white. Digital signal processing for image enhancement, manipulation and recording.
- Stereo imaging and analysis in the SEM - how to generate three dimensional information from two dimensional images.
- Specimen preparation for the SEM - inorganic and organic samples. Coatings and other special techniques.
- Xray microanalysis. Xray fluoresence by electrons. Mosley's law. The energy dispersive Xray detector and the multi-channel analyzer. Qualitive analysis. An introduction to quantitative analysis.
- Charging of poorly conducting samples in the SEM. The E2 condition. Low voltage microsocpy and environmental microscopy for insulators.
- Beam damage in the SEM - ionizing radiation, mass loss, and contamination.
The laboratory sessions will familiarize you with the SEM, loading and unloading samples, focussing, stigmation, and image recording. You will image a variety of specimens under a range of conditions and learn how to interpret the images. By about spring break you will start working on your class project. Your grade is determined from class assigments (20%), lab notebook (30%), and your project write-up (50%).