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Unformatted text preview: ated in t1 by νH only.
• FT with respect to t1 gives one 1H signal along the F1 axis with a
For 13CHCl3: For more complex molecules: 1H Chemical Shift 13C Chemical Shift 13 NOTE: 1) Easy to assign C signals if 1H signals are assigned, or vice
versa. 2) Little overlap of the correlation peak.
-7- 4. Two-Dimensional Homonuclear (H,H)-Correlated NMR
A) Pulse sequence Lets consider the case where Θx' = 90˚x' and lets consider a
homonuclear two-spin AX system.
First 90˚x' pulse:
• Tilt both vectors MA and MX along y'
• Due to JAX, MA has two components MA(Xα) and MA(Xβ), and MX
has two components MX(Aα) and
• νA (Xα) = νA - 1/2*JAX; νA (Xβ) = νA + 1/2*JAX
νX (Aα) = νX - 1/2*JAX; νX (Aβ) = νX + 1/2*JAX • ϕ(MA(Xα))=2π (νA - 1/2*JAX) t1; ϕ(MA(Xβ))=2π (νA + 1/2*JAX) t1
ϕ(MX(Aα))=2π (νX - 1/2*JAX) t1; ϕ(MX(Aβ))=2π (νX + 1/2*JAX) t1 • At the end of t1, the vectors have components along x' and y' -8- After the second 90˚x' pulse:
• The y and -y vector components are tilted along z and -z, which
results in polarization transfer. The transfer depends on t1,ν, an...
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- Fall '08