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

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Introduction
• NMR = Nuclear Magnetic Resonance.
• A material is to be analyzed by observing and measuring the
interaction...

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Basic Principles
• The nuclei of all atoms possess a nuclear quantum number, I. (I>0,
always multiples of 1/2.)
• Only nuc...

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NMR

  1. 1. NMR Spectroscopy H-NMR Spectra C-NMR Spectra Presented by : Ali Zia Roll No. : Bsf1702570
  2. 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. 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. 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. 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.
  6. 6. 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).
  7. 7. 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.
  8. 8. 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.
  9. 9. 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.
  10. 10. 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
  11. 11. 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
  12. 12. THANKS FOR LISTENING

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