scanningelektronmicroscopie

Scanning electron microscopy, often abbreviated as SEM, is a technique used to obtain high-resolution images of a sample's surface by scanning it with a focused beam of electrons. Unlike transmission electron microscopy (TEM), which passes electrons through a thin specimen, SEM analyzes the secondary electrons or other signals emitted from the sample's surface when the electron beam interacts with it. This interaction generates a signal that is detected and processed to create a detailed, three-dimensional-like image. The resolution of SEM is typically much higher than that of light microscopes, allowing for the visualization of very fine surface details.

The key components of an SEM include an electron gun, which produces the electron beam, electromagnetic lenses that focus and scan the beam across the sample, and a detector system that captures the emitted electrons or X-rays. The sample is usually placed in a vacuum chamber to prevent scattering of the electron beam by air molecules. Samples for SEM often require special preparation, such as coating with a thin layer of conductive material like gold or carbon, to prevent charging effects that can distort the image. SEM is widely used in various fields, including materials science, biology, geology, and forensic science, for examining the morphology, topography, and composition of a wide range of materials.