NMR Spectroscopy Flashcards
What is NMR Spectroscopy?
What is it used for?
Nuclear Magnetic Resonance.
Technique used for molecular structure determination and chemical analysis.
What is FTNMR?
What is it used for?
Fourier Transform Nuclear Magnetic Resonance.
a specific method of NMR that uses Fourier Transform for data processing.
How does MRI relate to FTNMR?
MRI is a medical application of NMR that uses the Fourier Transform technique to generate detailed images of the internal structures of the body.
What is magnetic resonance?
Magnetic Resonance is when certain particles (like atoms or electrons) respond to a magnetic field. They “resonate” or vibrate when exposed to a specific type of energy, like radio waves.
It is the underlying principle of techniques like NMR (for molecular structure analysis) and MRI (for medical imaging
What is NMR experiment?
Explain the key idea of atoms being tiny magnets.
Why can’t we feel/see the field?
How is it used for identification?
Nuclei generate tiny magnetic fields since they are positively charged and spin on an axis.
You cannot feel or see this magnetic field due to the amount that all point in different directions that are not strong enough.
This tiny magnetic field is characteristic to different elements so you can use it for identification.
What is NMR experiment?
Could you explain how the tiny magnetic fields go from random to either aligning/opposing?
How can you get the majority of nuclei to oppose magnetic field and why can’t you get all to do it.
Normally the tiny magnetic fields are randomly oriented. When placed in an external magnetic field, these tiny magnets align with or opposite it.
With the right pulse of energy (E=h) a majority of the the nuclei can be made to point opposite
to the magnetic field.
Not all can oppose as this is unnatural.
What is NMR experiment?
Explain what happens when energy supply is turned off.
How do bonding interactions affect energy and frequency?
As soon as the
pulse/energy is turned off , the nuclei will try to return to their original alignment.
You can measure how long this takes by getting frequency and calculating time.
Look at pattern and height of peak.
Different bonding interactions affect ease of flipping nuclear spin, so some bonds need less energy and the frequency is lower
What is precession frequency?
What does it depend on?
When do you get maximum frequency vs slower frequency?
The precession frequency is the rate at which this wobbling motion happens. It depends on the strength of the magnetic field and the type of nucleus.
maximum velocity/frequency when perfectly aligned.
Slower frequency with broader wobble than small wobble
What is Electron Shielding or Screening?
The electrons surrounding an atom also have magnetic properties. These electrons can partially shield or screen the nucleus from the full strength of the external magnetic field.
What is multiplicity?
Or splitting patterns.
refers to the splitting of NMR signals into multiple peaks due to the influence of neighboring protons.
reveal the number of adjacent protons
What are some common multiplicities?
Singlet (1 peak): No neighboring protons. The proton is isolated.
Doublet (2 peaks): One neighboring proton. The signal is split into two peaks.
Triplet (3 peaks): Two equivalent neighboring protons.
Quartet (4 peaks): Three neighboring protons.
