Download - Line Shape Analysis of NMR
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Line Shape Analysis of NMR
Alok ShauryaCHEM560
5th December, 2013
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CHEMICAL EXCHANGE
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OUTLINE
● NMR Spectra – From Bloch Equations to Line Shape
● McConnell Modification of Bloch Equations● Experimental Technique● Final Comments
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NMR - From Bloch Equations to Line Shape
Bo
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NMR - From Bloch Equations to Line Shape
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NMR - From Bloch Equations to Line Shape
T1
T2
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NMR - From Bloch Equations to Line Shape
Rotating frame
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NMR - From Bloch Equations to Line Shape
Lorentzian Line shape
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Chemical Exchange: McConnell Modification
Case study of a first order reaction
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Experimental Technique
● Record spectra at various temperature, find νA
and νB
● Simulate spectra, and find the best fit for the experimental data using regression analysis
● Extrapolate rates at different temperature and use them to draw Eyring or Arhenius plot.
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Experimental Technique
Various systems that have been studied using this technique
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Final Comments● Equations may seem dire but the underlying principles are
not...● This technique can only be used to study processes in
equilibrium. ● This technique can be used for any NMR active nuclei.● There are few softwares for simulation of NMR spectra
and line shape analysis on internet.● The final equation will change if the order of reaction
changes.● A quantum mechanical formalism (DFT based) of this
technique is in literature and is more powerful that classical approach.
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Further reading
● Dynamic NMR Spectroscopy, J. Sandstrom, Academic Press 1982
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THANK YOU