NMR

Question 1

What does NMR stand for?

Answer 1

Nuclear Magnetic Resonance

Question 2

What is the difference between spectroscopy and spectrometry?

Answer 2

Spectroscopy is the science of studying the interaction between matter and radiated energy while spectrometry is the method used to acquire a quantitative measurement of the spectrum.

• Spectroscopy does not generate any results. It is the theoretical approach of science. Spectrometry is the practical application where the results are generated.

Question 3

What is NMR spectroscopy?

Answer 3

a spectroscopic technique to observe local magnetic fields around atomic nuclei.

Question 4

Explain how NMR works?

Answer 4

-Nuclei consist of neutrons and protons which contain an intrinsic property called spin.

Question 5

What is the spin of 1H

Answer 5

1/2 (99.99%)

Question 6

What is the spin of 13C

Answer 6

1/2 (1.07%)

Question 7

What is the spin of 31P

Answer 7

1/2 (100%)

Question 8

What is the spin of 27Al

Answer 8

5/2 (110%)

Question 9

What is the spin of 29Si

Answer 9

1/2 (5%)

Question 10

What is the spin of 7Li

Answer 10

3/2 (92.4)

Question 11

What is the spin of gallium

Answer 11

3/2 (60%) 69Ga
3/2 (30%) 71Ga

Question 12

What is the preferred nuclei for Ga?

Answer 12

71Ga (fig. 4) is the gallium nucleus of choice as it is more sensitive and yields narrower signals than 69Ga.

Question 13

What determines the sensitivity of a nuclei

Answer 13

The constant gamma is characteristic for each isotope and is called the gyromagnetic ratio. The sensitivity of a nucleus in NMR depends on gamma (high gamma, high sensitivity).

Question 14

What is the spin of 19F

Answer 14

1/2 (100%)

Question 15

What determines the spin of a nuclei

Answer 16

A NMR sample contains many identical molecules (usually in a concentation range of mM for proteins). The spins of these molecules align indepently of each other parallel or antiparallel to the external field. The ratio of parallel spins to the antiparallel ones is given by the Boltzmann distribution:
Np / Nap = exp (DELTA E/(kT))