Dr. Saad B. H. Fa ridCharacterization of Materials Exercises 2013 1 |/ / Sample QuestionsLaser and Electron Microscopy 1-What are the advantages of the Scanning Laser Microscope? 2-What makes the right side of the adjacent micrograph better? 3-Draw signals resulting from interaction of primar y electron beam with specimen in an electron microscope. 4-Draw Electron yield versus atomic number for Backscattered ele ctrons and secondary electrons. Write a quick conclusion regarding SEM observation. 5-Which half (Left and right) ofthe following photo is observed via Secondary electrons and which is observed via Backscattered electrons? 6-What is the left hand and right hand SEM image resembles? 7-These are BSE micrographs of Pt particles on Alumina. Show the diff. between the le ft and right micrograph 8-Which is better in depth of field, the Secondary electr ons or the Back-scattered electrons? 9-What is the use of x-ray detection in electron microscopy? 10-What is the use of the scanning Auger microscopy? 11-What is your advice to observe distribution of Cu in welded steel BSE or SE? SEM images of Pt particles on alumina. The SE image (left) shows the morphology only, while the Pt particles appear with bright contrast in the BSE image (right)
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Dr. Saad B. H. Farid Characterization of Materials Exercises 2013 3 | / /
16- The following SEM micrographs (Mag: 1000×) showing the surface of the casting void in the fracture surface of
an aluminum casting. Show the difference between the (left) and (right) micrographs
(Left): Scanning Electron Microscope (SEM) image of the surface of a casting void in the fracture surface of an
aluminum casting
(Right): Scanning Electron Microscope (SEM) image of a brittle fracture surface in an aluminum casting
The angular particles in the surface are silicon particles that contribute to the brittleness of the material
17- Draw diagrams showing the difference between BF and DF imaging (page 9)
18- What is better in elemental analysis accompanied with EM? EDS or WDS? State why.
19- Draw schematically the main components for SEM and STEM.
20- State the sample thinning techniques for TEM observation In Brief.
21- State three dedicated applications of TEM.
Dielectric Characterization
1- Why LCR measurements for dielectric materials below 1MHz are nothing to do with dielectric materials
properties? What is really indicates.
2- High AC tension is applied at terminals of Porcelain specimen. Explain why lower leakage current is
observed for porcelains sintered at higher temperatures.
3- Does dielectric properties are reflected for centrosymmetric material? Why?
Spectroscopy AAS, OES, AFS, AMS and ICP
1- Distinguish Schematically (instrumental arrangements) between Atomic absorption and Atomic emission
spectroscopy.
2- Distinguish Schematically (instrumental arrangements) between Atomic absorption and Atomic
florescence spectroscopy.
3- What is the main difference Atomic emission spectroscopy and ICP-OES?
4-
What are the main stages that an aerosol gets throw before observation of emission lines in ICP?5- How can the backgrounds are extracted from Atomic spectroscopy measurements.
6- Are the intensities linearly or logarithmically related to concentrations in Atomic spectroscopy?
7- Sketch example calibration curve for ICP-OES?
UV-visible spectroscopy
1- Why UV-Vis spectra are not preferred for qualitative analysis?
2- What are the factors that affect the Intensity and absorption maxima of a chromophore? (they are 5)
3- State Beer’s law and explain the extinction coefficient, which factors affecting it?
4- Explain sample requirements and principle of additivity in spectroscopy.
5- Explain Least squares method for over-determined system in spectroscopy.