lecture16x-hetcor

1h 13c 2 12jch b spectrum after ft with respect

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Unformatted text preview: and MC{Hβ} to precess at the same rate during that time. 1H 13C ∆ 2 = 1/(2JCH) B) Spectrum • After FT with respect to t2, only one signal is observed in F2 with a frequency νC, and this signal is modulated in t1 by νH and JCH. • FT with respect to t1 gives two 1H signals ( νH - 1/2*JCH and νH + 1/2*JCH) along the F1 axis. -5- 3. Modified HETCOR Pulse Sequence to Remove Splitting in F1 and F2 A) Pulse sequence 1H 13C B) Vector Diagram • Insertion of a 13C 180˚x pulse in the middle of t1, which allows refocusing of MH{Cα} and MH{Cβ}. • Insertion of a delay 1/(2JCH) after t1 and before the second 1H 90˚x pulse. This constant delay is needed for optimal population transfer. After a delay of 1/(2JCH) MH{Cα} and MH{Cβ} have a 180˚ phase difference. • The magnitude of the polarization transfer depends only on ϕ, which is independent of JCH. ϕα = ϕβ = 2π (νH) t1 a b c d e f -6- C) Spectra • FT with respect to t2 gives one 13C signal along the F2 axis with a frequency νC, and this signal is modul...
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This note was uploaded on 11/13/2011 for the course CHEM 4190 taught by Professor Staff during the Fall '08 term at UGA.

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