In order tostudy and develop different new materials, optical microscope is needed tosomehow to see what is happening in the microscopic scale. However, in order toexamine structures inside cells, electrons should be used instead of photonsand one of the latest additions to materials engineering practice is the scanningelectron microscope (SEM).The SEM is apowerful microscope that uses electrons instead of light to view objects ingreat detail.
The shorter wavelength of electrons permits useful magnificationsof up to about 1000x versus only about 2000x for light microscopy. The SEM alsoprovides much greater depth of field than light microscopes allowing complexthree dimensional materials to remain sharp and in focus. This gives thematerial being examined life-like appearance and reveals details that would notbe seen by light microscopy. Scientists can magnify objects up to about ahundred thousand times and take high quality digital photographs of everythingthey see.
Furthermore, the ESM can be coupled with EDS system to identify andevaluate the chemical composition and the crystal structure of samples. WithSEM, scientists can determine the structure of viruses, i.e. protein complexeswith very high resolution in their laboratories. It is very important forscientists to have structures with very high resolution so they can explain themechanisms of infection for viruses or of the actions of protein complexesinvolved in important biological processes inside the cell.
In materialscience, SEM is an important technique to characterize surface features ofmaterials, examine contaminants to understand their origins and the effectsthey have on engineering materials, examine the microstructures of metals andalloys to help determine how they will perform in service or what serviceconditions have done to these materials. SEM can also be used to examinecoatings and surface films to identify their chemical composition, thicknessand the nature of their bond with the parent material. These are just a tiny ofthe many types of sample and materials that can be examined with SEM. To summarize, ascanning electron microscope is one of the best ways to look at objects veryclosely and an excellent way to test the composition and the quality of amaterial. The most frequent spectroscopic technique used byorganic and inorganic chemists is IR spectroscopy or Infrared spectroscopy.
Itdeals with the absorption of radiation in the infrared region of theelectromagnetic spectrum. IR spectrum gives sufficient information about thestructure that it is helpful in the identification of functional of aparticular compound and it can also be used as analytical tool to access thepurity of a compound. The absorption of the infrared radiation by a moleculecauses changes in their vibrational and rotational energy levels. IRspectroscopy provides spectrum with a large number of absorption and henceprovides plenty of information about the structure of a particular compound.There are different bands present in the IR spectra which correspond to variousfunctional groups and bonds which are present in that particular molecule.Infrared spectroscopy goes beyond for the use, notonly for organic chemist but also for many other fields. Infrared spectroscopyis a simple and reliable technique which widely is used in both organic andinorganic chemistry.
It is also used in quality control analysis, in industrialscientific and medical applications. For example, FTIR technique is one way wecan verify the authenticity for wide range of building materials. When infraredradiation from a laser beam hits a material, the molecules of the materialbegin to move and vibrate in a very characteristic way that can be used toidentify them, this is the basis of technology based of FTIR spectroscopy. Wecan think of the information we get from FTIR spectroscopy as a molecularfingerprint. The fingerprint we get as outputs from FTIR experiments are calledspectra and we can use these spectra to identify unknown materials.