CHEM 3AL Lecture Notes - Lecture 9: N-Gram, Chemical Shift
(10 )NMR Nuclear magnetic resonance )
spectroscopy
:
(reading 8.1 -8.13 (8.14 optional &more in-depth)
*
Technique to probe molecular structure using EM radiation (Hv light interacts Mmolecules )
*
rays
Wins infrared microwave Radio
ENERGY
core e- outer e- vibrations Rotations spin
transitions Transitions
-NMR spin Tuuroitious :based on existence of nuclear spin G)
(spin
-in other words -is NNR Active )
examples :Ei spin \
'
H±
2. ±
g
www.nwwafmamiEY
*NIimprove signal .
1°F tz
up tz
-
spinning charge In Nucleus generates Magnetic Field (BField )
-Nucleus hah a
magnetic
moment
-man External aApplied BField there are 2spin status ltt )
-the higher energy fights AGARNST Apputd Magnetic Field (Bo )
-the lower
goes with Bo
-The point Is that Bo will exile 2separate energy ayes .
^I
2then look for peaks caused by Bo :
⇒bfe badio frequency )}-±
-+-
Einput
\
-+t-→
zRF impulse
o>)+E#+#
applied BField
(Bo )
-scan through E
range to detect an transitions associated with sample
-characteristics of pears give info .about Amare .
integral tins now many nuclei are responsible for signal .
-
chemical shift (8) tells about electronic environment of mums .
(elections shield from Bo so energy ditfhce )
-Multiplicity tens about peak shape differs (dittnenut Magnetic ineqwivalenw )
