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The images obtained in the scanning electron microscope are produced by secondary electrons or backscattered electrons emitted as a result of the interaction between an incident beam of 5 to 30 KeV and the sample.
As a result of the scanning of an electron beam across the surface of the sample in XY, an image can be formed on the monitor. The brightness of each point on the screen is proportional to the signal emitted by the sample at that point.
The secondary electron signal is emitted from a thin layer of the surface ranging from 50 to 100 Å. Low-energy electrons, less than 50 eV, can be easily deflected from their emerging trajectory giving information from areas hidden to the detector. So the signal can provide information about the topography of the sample.
The backscattered electron signal depends strongly on the atomic number of the sample. This means that two parts of the sample with different composition appear with different intensity even if there is no difference in topography between them.
The X-rays generated from the scattering of the electron beam in the sample allow the identification of the elements present in the sample and their concentration.
There are many applications of the technique both in materials science and biomedical science. Materials science applications include metallurgy, petrology and mineralogy, building materials, traditional and advanced ceramics, electronics, fractography, composites and the study of elemental composition of surfaces and solids in general. The SEM is also used in botanic, in the study of cell cultures, in dermatology, in biomaterials, in odontology, in hematology, in immunology, and in the study of the morphology of biomedical preparations in general.
Co-financed by 80% by the ERDF 2007-2013 of the Comunitat Valenciana and 20% by the Generalitat Valenciana
Equipment for sample preparation:
-Critical point dryer ELECTRON MICROSCOPY SCIENCES EMS 850.
-Metallizer (Au)/Evaporator (C) Balzers SCD 004
-Metallizer/Evaporator Balzers MED 020