cems.pptx

cems.pptx

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  Presented by : Komaljain M . Pharm (PHARMACEUTICAL CHEMISTRY)
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  o History o Introduction oMossbauer effect o Principle o Instrumentation o Spectrum of cems o Application
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  • 1957 →Rudolf Mossbauer achieved 1st experimental observation of resonant adsorption of γ-radiation and discovered recoil free in solid emission. • Discovered "Mossbauer Effects in 1958. • Mossbauer spectroscopy is also known as NUCLEAR GAMMA RESONANCE SPECTROSCOPY.
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  • It isa technique of spectroscopy that uses the mossbauer effect , which is the recoil free resonance absorption and emission of gamma rays of solids. No
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   How doesit work • Nuclei in atoms undergo many energy level transitions. Changes occur due to emission and absorption of a gamma ray. • Energy levels are determined by the nuclei's surrounding environment. Observed using nuclear resonance fluorescence. • Special technique used to gauge distances between chromophores • Only works when separation distance is less than10nm • The Mossbauer Effect is a process in which a nucleus emits or absorbs gamma rays without loss of energy to a nuclear recoil. Recoil-free emission or absorption of a gamma-ray when the nuclei are in a solid matrix such as a crystal lattice
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   The basicelements of the Mossbauer spectroscopy are: 1. Source 2. Sample 3. Collimator 4. Detector 5. Drive to move the source
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  • It isformed by three main parts: • A source that moves back and forth to generate a doppler effect. • A collimator that filters out non-parallel gamma rays and, • A detector.
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  There are threetypes of nuclear interactions that are observed are : 1. Isomer shift (IS) 2. Quadrupole shift (QS) 3. Magnetic shift (MS)
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   General formof an isomer shift  Single peak  Slightly shifted from zero  Can be positive or negative
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   Shows twosamples  Both show quadrupole splitting  Show how similar structures give similar signals.
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   In presenceof a magnetic field.  This magnetic field is often called the hyperfine field.  Nuclear spin moment feels a dipole interaction through Zeeman splitting. Zeeman splitting:  Atomic energy levels are split into a larger number of energy levels.  Magnetic field applied to split energy levels.  Spectral lines are split along with atomic energy levels.
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   Steel corrosionanalysis  Metal alloy characterization  Ultra thin film analysis  Surface analysis  Spray Deposition(SD)Technique.  Artificial oxide films  Surface and interface reaction  Ion implanted layers
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   CEMS isa highly-selective and non-destructive method.  Conversion electrons are very easy to detect efficiently.  Information on the configuration of magnetic spin in the surface layer can be obtained.  CEMS has become an important tool of materials surface analysis.
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   Loss ofelectron energy in their passage through matter cannot be calculated.  Compton scattering and the photoelectric effect produce "non-resonant electrons".  Electrons do not move through matter in straight lines.  Only windowless detectors may be used.
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   https://wiki.umn.edu/MXP/MossbauerLabIntroduction  MossbauerSpectroscopyinMaterialScience,MarcelMiglieri ni,Dimitris.  http://korek.uci.agh.edu.pl/cemsnew.html  Mossbaueur1,StructuralInvestigation and Characterization of Materials, Carlos familyname.  http://phobos.chemie.uni-mainz.de/moessbauer.php.