Protons have much smaller chemical shift anisotropics than heteronuclei, but at the very high magnetic fields which

Question:

Protons have much smaller chemical shift anisotropics than heteronuclei, but at the very high magnetic fields which are now becoming available CSA relaxation may be significant. Assuming that a proton has = 10ppm, calculate the CSA contribution to its transverse relaxation at fields of 4.7 T, 11.74 T and 23.5 T (the latter field corresponds to a proton Larmor frequency of 1000 MHz); in your calculation, assume that the fast motion limit applies, and take Ï„c = 20 ps. Compare your values with the rate constants for dipolar relaxation calculated for the same correlation time in exercise 9.8.