it is about brief introduction of NMR spectrum

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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