Wie funktioniert ein Raster - Elektronenmikroskop?
A scanning electron microscope (SEM) is a type of microscope that uses electrons to image the surface of a sample with high resolution. Here's a brief overview of how an SEM works:
Electrons are generated: An electron gun at the top of the SEM produces a beam of high-energy electrons. This beam is focused by a set of electromagnetic lenses.
Electrons interact with the sample: The electron beam is directed onto the surface of the sample, where it interacts with the atoms in the material. When electrons from the beam collide with atoms on the surface of the sample, they can cause other electrons to be emitted from the material. These emitted electrons are called secondary electrons.
Secondary electrons are detected: A detector in the SEM detects the secondary electrons emitted by the sample. By scanning the electron beam across the surface of the sample and detecting the secondary electrons emitted from each point, an image of the sample's surface can be formed.
Image is created: The SEM creates an image by converting the detected secondary electrons into a signal that can be displayed on a computer screen. The signal is typically converted into a grayscale image, where the brightness of each pixel corresponds to the intensity of the secondary electrons emitted from that point on the sample.
SEM images have high resolution and can reveal details at the nanoscale. They are commonly used in materials science, biology, and other fields to image the surface of samples and study their structure and properties.