![]() The crystal structure of samples with regular atomic structure (crystalline material) may also be analysed via electron diffraction. By rotating a sample, and taking multiple images at each rotation, it is also possible to build a 3D representation of the specimen (tomography). The intensity of un-scattered electrons gives rise to a "shadow image" of the specimen, with different parts of a specimen displayed in varied darkness according to density. Traditional bright field imaging relies on incident electrons being scattered and disappearing from the beam depending upon the compositional density and crystal orientation of the sample. The electrons passing through the specimen then impact on a detector. Electromagnetic lenses are used to focus the electrons into a very thin beam and this is then directed through the specimen of interest. ![]() An electron source at the top of the microscope emits electrons that travel through a vacuum in the column of the microscope. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |