lecture16x-hetcor

Population transfer from 1h to 13c as in spi and

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Unformatted text preview: and JCH. • Population transfer from 1H to 13C as in SPI and INEPT, although here the transfer depends on t1. After the 13C 90˚x' pulse: • Turns the two longitudinal 13C vectors +z and -z into the +y' and -y' directions, respectively. • Two frequencies are detected by the receiver: νC - 1/2*JCH νC + 1/2*JCH -3- B) Spectrum • FT with respect to t2 gives two 13C signals ( νC - 1/2*JCH and νC + 1/2*JCH) along the F2 axis (one positive and one negative);these signals are 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) for each 13C signal along the F1 axis. • 2D NMR spectrum has therefore 4 signals, 2 with negative amplitude. 1 • H decoupling during acquisition would remove the signal -4- 2. Modified HETCOR Pulse Sequence to Remove Splitting in F2 A) Pulse sequence • Insertion of a delay 1/(2JCH) between the 13C 90˚x pulse and the acquisition of the FID, which allows refocusing of MC{Hα} and MC{Hβ}. • BB decoupling during acquisition cause MC{Hα}...
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