Now, we will study about scanning electron microscope or sem for short. Sem is a type of electron microscope that produces images of a scatter sample by scanning it with a focused beam of electrons. Here is a brief outline of scanning electron microscope or sem. We will begin with the use of sem, how it works, the pathway of electron beams. Then, we will look at the resolution magnification and other aspects of sem. Next we'll look at the SEM machine and examples of sem images.
Sem is a type of electron microscope that produces images of a sample by scanning the surface of the sample with a focused beam of electrons. Here's how it works First, the sun is placed in the vacuum chamber and covered with a coat of gold. Then the electron beam scans across the specimen and locks loose showers of electrons that are captured by a detector. The electrons interact with atoms in the samples, producing various signals that can be detected and contain information about the sample surface topography and composition and image bill sub line by line as in a television receiver. The electron that strikes a sloping surface yield fewer electrons and therefore produce darker contrasting spots and create a sense of three dimension. Shown here is the pathway of the electron beam.
The vacuum chamber spans from the electron gun all the way to the stage. electron beam passes through an anode. And then through the magnetic lens, the spanning scanning coils that is, and after the electrons hit the specimen, they're detected by a detector electron detector the back scattered electrons there is and then a secondary electron detector. And these electrons interact with the atoms in the samples producing various signals that can be detected and contain information about this sample surfaces typography and composition which are detected by the PVS scanner. The resolution of sem is at 10 nanometers, its magnification is limited to 20,000. The sem gives information About the surface topography and composition of the sample.
It gives vivid undistorted views of the organisms surface details. Shown here is an example of an FCM machine, one at the bottom and another one over here. And Shown here are examples of sem images. Figure a is of equal ly a common bacterial cause of dysentery diarrhea, we have Clostridium tetany that causes tetanus see of methicillin resistant Staphylococcus aureus one bacteria that is recently emerging and is increasingly causing challenges with antibiotic resistance and be nice area meningitis or many caucus which causes meningitis. So in summary, sem is used to get information on the surface topography and composition it produces vivid undistorted images of surface details. It is used to visualize lies the surface of unsanctioned specimen coated with gold.
The LCM machine includes a vacuum chamber, electron beam and a detector. It produces a 3d image, the SEM can magnify the specimens image up to 20,000 times its resolution power is of 10 nanometers. This concludes our study of sem