SCANNING ELECTRON MICROSCOPY Research Technical Services

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Research Technical Services

SCANNING ELECTRON MICROSCOPY

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.

 

Applications

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.

 

Equipment

sem hitachi

 

 

  • Field emission scanning electron microscope (FESEM) Merlin VP Compact from Zeiss equipped with an EDS microanalysis system Quantax 400 from Bruker. The resolution is 0.8 nm at 15 kV and 1.6 nm at 1 kV. Field emission equipment is able to work at voltages very reduced (from 0.02 kV to 30 kV) allowing to observe beam sensitive samples without damaging them and minimizing the charging effects.

 

 

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

 

Sample requirements