NMR spectroscopy is a technique that uses nuclear magnetic resonance to analyze materials. It is a non-destructive technique that requires less sample preparation than other methods like mass spectrometry. 1H NMR spectroscopy specifically analyzes hydrogen nuclei and provides information about the number, type, and neighboring atoms of hydrogens in a molecule. Similarly, 13C NMR spectroscopy analyzes carbon atoms and can reveal a molecule's structure based on the chemical shifts of different carbon types. Both techniques yield quantitative data and details about molecular composition and dynamics.

1. NMR Spectroscopy
H-NMR Spectra
C-NMR Spectra
Presented by : Ali Zia
Roll No. : Bsf1702570

2. Introduction
• NMR = Nuclear Magnetic Resonance.
• A material is to be analyzed by observing and measuring the
interaction of nuclear spins when placed in a powerful magnetic field.
• Sample measurements are non-destructive.
• There is less sample preparation required.
• Compared to mass spectrometry, large amounts of sample are
needed

3. Basic Principles
• The nuclei of all atoms possess a nuclear quantum number, I. (I>0,
always multiples of 1/2.)
• Only nuclei with spin number (I) >0 can absorb/emit electromagnetic
radiation.
• Fermions : Odd mass nuclei with an odd number of nucleons have
fractional spins.
I = 1/2 ( 1H, 13C, 19F, 31P ), I = 3/2 ( 11B, 33S ) & I = 5/2 ( 17O )
• Bosons : Even mass nuclei with odd numbers of protons and neutrons
have integral spins
I = 1 ( 2H, 14N )

4. Basic Principles
• Even mass nuclei composed of even numbers of
protons and neutrons have zero spin
I = 0 (12C, and 16O, 32S
• The spinning nuclei possess angular momentum, P,
and charge, and so an associated magnetic
moment, µ .
𝜇 = 𝛾𝑃
where 𝛾 is gyromagnetic ratio.

5. Basic Principles
• When a nucleus that
possesses a magnetic
moment (such as a
hydrogen nucleus 1H,
or carbon nucleus 13C)
is placed in a strong
magnetic field, it will
begin to precess, like a
spinning top.

8. Criteria for NMR
• Nuclei should have spin quantum I>0
• We should apply external magnetic field
• We should supply energy in the form of EMR that
resonates with energy gap(Radio waves).

9. What we can learn from NMR spectra
• Chemical shift: Information about the composition of atomic
groups within the molecule.
• Spin-Spin coupling constant: Information about adjacent
atoms.
• Relaxation time: Information on molecular dynamics.
• Signal intensity: Quantitative information, e.g. atomic ratios
within a molecule that can be helpful in determining the
molecular structure, and proportions of different compounds in
a mixture.

10. H-NMR spectrum
• Proton nuclear magnetic resonance (proton
NMR, hydrogen-1 NMR, or 1H NMR) is the
application of nuclear magnetic
resonance in NMR spectroscopy with respect
to hydrogen-1 nuclei within the molecules of a
substance.

11. Information from 1H-nmr spectra:
• Number of signals: How many different types of hydrogens in the
molecule.
• Position of signals (chemical shift): What types of hydrogens.
• Relative areas under signals (integration): How many hydrogens of
each type.
• Splitting pattern: How many neighboring hydrogens.

12. C-NMR
• We can examine the nuclear magnetic properties of carbon atoms in
a molecule to learn about a molecules structure.
• Most carbons are 12C; 12C has an even number of protons and
neutrons and cannot be observed by NMR techniques. Only 1% of
carbons are 13C, and these we can see in the NMR.
• The most significant factors affecting the chemical shifts are:
1. Electronegativity of the groups attached to the C
2. Hybridisation of C

13. References
• https://www.jeol.co.jp/en/products/nmr/basics.html
• Nuclear Magnetic Resonance (NMR) Spectroscopy By_ Saurav k. Rawat
School of Chemical Science, St. John’s College.
• https://www.sciencedirect.com/topics/chemistry/1h-nmr- spectroscopy

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