2536642
Descrição
Mapa Mental por Kathryn Bellis, atualizado more than 1 year ago
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Criado por Kathryn Bellis
mais de 9 anos atrás
|
|
Nuclear
Magnetic
Resonance
Spectroscopy
- What is NMR?
- Many atomic nuclei behave as
though they are spinning - this
is called NUCLEAR SPIN.
- Such nuclei have a magnetic moment which means they behave like tiny bar magnets.
- When an external magnetic field is
applied the nuclei which have spin will
line up in the either the same direction
(with the field) or the opposite direction
(against the field.
- The nuclei aligned with the field are much lower in energy
that the ones against it.
- A signal is recorded when
a nucleus aligned wit the
magnetic field absorbs
low-energy radiation in
the radio-frequency range
and the nucleus enters
the higher energy state.
- This is called RESONANCE
- This is called RESONANCE
- A signal is recorded when
a nucleus aligned wit the
magnetic field absorbs
low-energy radiation in
the radio-frequency range
and the nucleus enters
the higher energy state.
- The nuclei aligned with the field are much lower in energy
that the ones against it.
- When an external magnetic field is
applied the nuclei which have spin will
line up in the either the same direction
(with the field) or the opposite direction
(against the field.
- Such nuclei have a magnetic moment which means they behave like tiny bar magnets.
- Many atomic nuclei behave as
though they are spinning - this
is called NUCLEAR SPIN.
- Hnmr Spectroscopy
- In organic molecules, protons are
surrounded by ELECTRONS, which
partially shields them from the
applied magnetic field.
- The amount of shielding
depends on the electron density
surrounding the nucleus and
varies for different protons
within a compound.
- Factors which affect ELECTRON
DENSITY:
- Bond Polarity
- The presence of
electron
donating groups
- The presence of electron withdrawing groups
- Bond Polarity
- Factors which affect ELECTRON
DENSITY:
- The amount of shielding
depends on the electron density
surrounding the nucleus and
varies for different protons
within a compound.
- As each chemically distinct H
atom has a unique electronic
environment it gives rise to a
characteristic resonance
- Chemically Equivalent
Protons are all in the same
environment and
therefore absorb the same
frequency
- Chemically Equivalent
Protons are all in the same
environment and
therefore absorb the same
frequency
- In organic molecules, protons are
surrounded by ELECTRONS, which
partially shields them from the
applied magnetic field.
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