Na-20 Nuclear Magnetic Resonance
AIM
To demonstrate Nuclear Magnetic Resonance using Magnetic Field and RF field and a few samples of Glycerine, Polystyrene and Teflon. These have an odd number of neutrons or protons in the Nucleus.
APPARATUS
- ESR/NMR Basic Unit
- 1 Pair of Magnetic Coils
- 1 Control Console
- Dual Channel Oscilloscope
- NMR Probe Unit
- Blank Sample
- Glycerine
- Polystyrene
- Teflon
DESCRIPTION
With the NMR Probe Unit connect to the Control Console, which is connected to a Dual Channel Oscilloscope. One Channel is the output of the Field of Coils, while the output is signal of the sample. When one the above samples is placed in the NMR Probe Unit, a spike in the signal is observed when the one neutron or proton is flipped when the critical magnetic field strength is reached during the sweeping of the frequency range. Nucleons of an atomic nucleus structure have an intrinsic quantum property of spin. Normally when an external magnetic field is applied, neutrons of protons will naturally align themselves with the applied magnetic field. This quantum state is known as spin up. If a nucleon gains energy from an applied RF field, the nucleon will align itself 180° against the applied magnetic field. This quantum state is known as spin down. The nucleon will return to its lower energy quantum state, spin up. Energy in RF range will be released. Which will be observed as a spike on the oscilloscope on the channel which connect to output signal of NMR Probe Unit. are Which can be varied using the Control Console.
The Resonant Frequency of the material samples
Glycerine (1H) 42.58 MHz/T
Polystyrene (1H) 42.58 MHz/T
Teflon (19F) 40.06 MHz/T
The Control Console applies a sweeping DC magnetic field across the coils in a small range.
The RF values for the materials are
Glycerine = 12.854 MHz
Polystyrene = 12.8854 MHz
Teflon = 12.100 MHz
These values can vary for differing the Magnetic field strengths
When the Blank Sample is inserted in the ESR Probe Unit, a spike will not be observed in the output signal.