CHAPTER 9 NOTES

CHAPTER 9 NOTES - CHAPTER 9 NUCLEAR MAGNETIC RESONANCE...

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CHAPTER 9 NUCLEAR MAGNETIC RESONANCE - - INTRODUCTION - - 1 H NMR - - 13 C NMR - - OMIT SECTIONS: 9.12 9.17 - - MASS SPECTROSCOPY
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INTRODUCTION: - - NUCLEI OF CERTAIN ISOTOPES ( e.g., 1 H , 13 C ) BEHAVE LIKE MAGNETS SPINNING ABOUT AN AXIS - - WHY ? - - CHARGED PARTICLE ( p + ), SPINNING MAGNETIC MOMENT ( LIKE A TINY BAR MAGNET ) ( cf. SPINNING e MAGNETIC MOMENT ) - - SEE FIG. 9.8 p. 375 - - WHEN PLACED IN AN EXTERNAL MAGNETIC FIELD - - THE p + CAN ORIENT: ( α 29 WITH THE EXTERNAL FIELD OR ( β 29 AGAINST THE EXTERNAL FIELD - - SEE FIG. 9.9 p. 375 - - E BETWEEN α β STATES STRENGTH OF EXTERNAL FIELD IF : E = E IS SUPPLIED , ( i.e., MAGNETIC RESONANCE ) - - WHAT MIGHT HAPPEN ? - - E FOR MOST NUCLEI: - - CORRESPONDS TO THE ENERGY OF RADIOWAVES ( SEE FIG. 9.2, p. 369 )
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- - SO ? - - E (= E) CAN BE SUPPLIED BY IRRADIATION OF THE COMPOUND WITH RADIOWAVES - - THE E WILL BE ABSORBED BY THE COMPOUND, - - CAN BE USED FOR ANALYSIS NOTE: - - IF ALL ( 1 H; 13 C ; etc. ) ATOMS IN A MOLECULE HAD IDENTICAL E VALUES, NMR WOULD BE WORTHLESS ! ( AS A STRUCTURE DETERMINATION TOOL ) - - WHY ? - - THERE WOULD BE NO WAY TO DISTINGUISH BETWEEN THE DIFFERENT ATOMS
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HOWEVER, - - E VALUES FOR DIFFERENT 1 H (OR 13 C ) ATOMS ( IN THE SAME MOLECULE ) ARE SLIGHTLY DIFFERENT - - WHY ? -
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This note was uploaded on 04/14/2008 for the course CHEM 2370 taught by Professor Dandekar during the Fall '07 term at North Texas.

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CHAPTER 9 NOTES - CHAPTER 9 NUCLEAR MAGNETIC RESONANCE...

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