lecture5_product_operator_II

lecture5_product_operator_II - A. S. Edison University of...

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Unformatted text preview: A. S. Edison University of Florida 2008 Todays Lecture 6) Fri, Oct 10: Product operators II a. Scalar (J) coupling b. Multiple pulse experiments A. S. Edison University of Florida 2008 J coupling and chemical shift example 1 H NMR 1D spectra of Methyl -D-Arabinofuranoside in CD 3 CN. Collected at 11.7 T by Jim Rocca in AMRIS. All of the splittings are J couplings A. S. Edison University of Florida 2008 J coupling Normal spectrum Decouple 4.93 ppm Decouple 4.05 ppm J coupling allows you to identify atoms within 3 (sometimes more) covalent chemical bonds. This will be even more powerful when we get to 2D NMR experiments. A. S. Edison University of Florida 2008 Why are J coupling values different? Martin Karplus showed that J from vicinal coupled 1 H atoms depends on the dihedral angle between the protons. This relationship can be approximated by the famous Karplus equation : C B A J + + = 29 ( 29 ( 29 ( 2 A , B , and C are empirically derived parameters. J couplings provide an estimation of molecular conformation! J( ) A. S. Edison University of Florida 2008 Last lecture we discussed rotations of bulk magnetization. r r r r r r r r r r = 1 Mx B B B B B B B B B B = 1 My B B B B B B B B B B = 1 Mz x y z x y z x y z x y z x y z x y z This was the example of a rotation of Mz around the x-axis by an angle . The vector went toward the y axis. . . . . . . . . . .- = + +- + + + =- ) ( ) ( ) ( ) ( 1 ) ( ) ( ) ( ) ( 1 f f f f f f f f Cos Sin Cos Sin Cos Sin Sin Cos A. S. Edison University of Florida 2008 Now we get a bit more complicated How many states does a spin particle have?...
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lecture5_product_operator_II - A. S. Edison University of...

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