Question

a)Calculate the Larmor frequency of ¹³C and ¹H in an MRI machine with magnitude of the magnetic field 1.7 T. Please take the gyromagnetic ratio of ¹³C and ¹H nuclei to be 10.7 MHzT^-1and 42.5 MHzT^-1, respectively.

b)Why do you think, when a group of spins is driven into higher energy levels by an RF field, these spins do not immediately release the absorbed energy and drop back to their original lower energy states?

c)Name most common isotopes used in NMR. What are the advantages and disadvantages over ¹H?

Answer 1

Larmor frequency is given by

Where is the gyromagnetic ratio

So

Larmor frequency of hydrogen

Similarly for 13C

isotopes

isotopes of Hydrogen are used tritium is radio active so we wont use often.

1H has sharp signals compare to 2H

Sulfur has 4 isotopes 32S,33S, 34S and 36S