2. principles of spectroscopy uv and ir - copy - copy
TRANSCRIPT
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8/6/2019 2. Principles of Spectroscopy UV and IR - Copy - Copy
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by
UV, IR, NMR AND MASS SPECTROMETRIES
Identification of Compounds
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Gas Chromatogram of Flavor Compounds
5
1516
1
10 11
13
17
9
3
6
7
8
14
12
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Identification of Compound
H2
CH3
CH3
CH3
H3C
H2 H
HH
HH
O
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SPECTROMETRIC IDENTIFICATION
I. Introduction of Spectrometric AnalysesII. Ultra Violet Spectrometry
III. Infrared Spectrometry
IV. Nuclear Magnetic Resonance Spectrometry
V. Mass Spectrometry
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I. Introduction of Spectrometric Analyses
The study how the sample interacts with different
wavelength in a given region of electromagnetic radiation
is called spectroscopy or spectrochemical analysis.
The collection of measurements signals (absorbance) as a
function of electromagnetic radiation is called a spectrum.
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Spectrum of Radiation
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Electromagnetic Spectrum.
Wavelength,, cm
frequency, , (cycles/sec)
-ray
-ray
ultravio
let
visibl
e
infrare
d
microwave
radio
violet
blue
green
yellow
orange
red visible region
400 500 600 700 800
1020
1018
1016
1014
1012
1010
108
106
104
102
10-10
10-8
10-6
10-4
10-2
1
102
104
106
108
Wavelength,, nm
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Energy Absorption
The mechanism of absorption energy is different in the
Ultraviolet, Infrared, and Nuclear Magnetic Resonance
regions. However, the fundamental process is the absorptionof certain amount of energy.
The energy required for the transition from a state of lower
energy to a state of higher energy is directly related to the
frequency of electromagnetic radiation that causes the
transition.
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Spectral Distribution of Radiant Energy
V' = Wave number (cm-1
) = Wave length (nm)C = Velocity of Radiation (constant) 3 1010 cm/secV = Frequency of Radiation (cycles/sec)
V' = =
(The energy of photon) E = Vh(Planck's Constant 6.62 10-27 erg - sec )
E = Vh = h
C = V
V =
C
V
1
C
C
1 x 107erg = I joule
=0.239 calorie
Avogadros number = 6.02
x 10 23 mol-1
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Visible
Ultra
violet
Radio
Gamma
ray
EnergyWave
Number VWavelength
Frequency
TypeRadiation
Typespectroscopy
TypeQuantum Transition
Kcal/mol
Electronvolts,
eV cm-1
cm Hz
9.4 x 107 4.9 x 106 3.3 x 1010 3 x 10-11 1021
9.4 x 103 4.9 x 102 3.3 x 106 3 x 10-7 1017
9.4 x 101 4.9 x 100 3.3 x 104 3 x 10-5 1015
9.4 x 10-1 4.9 x 10-2 3.3 x 102 3 x 10-3 1013
9.4 x 10-3 4.9 x 10-4 3.3 x 100 3 x 10-1 1011
9.4 x 10-7 4.9 x 10-8 3.3 x 10-4 3 x 103 107
X-ray
Infrared
Micro-
wave
Gamma ray
emission
X-rayabsorption,
emission
UV absorption
IR absorption
Microwave
absorption
Nuclear
magnetic
resonance
Nuclear
Electronic(inner shell)
Molecular
vibration
Electronic
(outer shell)
Molecularrotation
Magnetically
induced spin
states
Spectral Properties, Application and Interactions of Electromagnetic Radiation
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Molecular Orbital of Triplet Oxygen
MolecularAtomicAtomic
2Pz 2Py 2Px2Px 2Py 2Pz
*
* *
2S2S
1S1S
*
*
Energy
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Principal quantum number (n): The average distance of the
electron from the nucleus. 1, 2, and so on.
Azimuthal quantum number (Momentum quantum number)
(l): The shape of the orbital. 1s, 2s, 2p, 3s, 3p, 3d, etc
Magnetic quantum number (Orientational quantum number)
(ml): The orientation of orbital in the space. 2px 2py, 2pz x, y
and z are orientational quantum number
Electron spin quantum number (ms)= The two possible
orientation of the electron in a magnetic field. 1/2 or 1/2
Quantum Numbers and Orbitals
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One S and Three P Orbitals
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The 5 d Orbitals
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II. Ultra Violet Spectrometry
The absorption of ultraviolet radiation by
molecules is dependent upon the electronicstructure of the molecule. So the ultraviolet
spectrum is called electronic spectrum.
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Visible
Ultra
violet
Radio
Gamma
ray
EnergyWave
Number VWavelength
Frequency
TypeRadiation
Typespectroscopy
TypeQuantum Transition
Kcal/mol
Electronvolts,
eV cm-1
cm Hz
9.4 x 107 4.9 x 106 3.3 x 1010 3 x 10-11 1021
9.4 x 103 4.9 x 102 3.3 x 106 3 x 10-7 1017
9.4 x 101 4.9 x 100 3.3 x 104 3 x 10-5 1015
9.4 x 10-1 4.9 x 10-2 3.3 x 102 3 x 10-3 1013
9.4 x 10-3 4.9 x 10-4 3.3 x 100 3 x 10-1 1011
9.4 x 10-7 4.9 x 10-8 3.3 x 10-4 3 x 103 107
X-ray
Infrared
Micro-
wave
Gamma ray
emission
X-rayabsorption,
emission
UV absorption
IR absorption
Microwave
absorption
Nuclear
magnetic
resonance
Nuclear
Electronic(inner shell)
Molecular
vibration
Electronic
(outer shell)
Molecularrotation
Magnetically
induced spin
states
Spectral Properties, Application and Interactions of Electromagnetic Radiation
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Electronic Excitation
The absorption of light energy by organic compounds in the
visible and ultraviolet region involves the promotion ofelectrons in , , and n-orbitals from the ground state tohigher energy states . This is also called Energy Transition.
These higher energy states are molecular orbitals called
antibonding.
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Types of Bonds
Energy
*
*
n
*
*
n
*
n
*
Antibonding
Antibonding
Nonbonding
Bonding
Bonding
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Electronic Molecular Energy Levels
The higher energy transitions ( *) occur a shorter
wavelength and the low energy transitions ( *, n *) occur at longer wavelength.
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Electronic Ground and Excitation States
* *
hv
*
hv
*
n
hv
*
hv
*
n
*
Energy
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Chromophore is a functional group which absorbs a
characteristic ultraviolet or visible region.
210 nm Double Bonds
233 nm Conjugated Diene268 nm Conjugated Triene
315 nm Conjugated Tetraene
and* orbitals and* orbitals
Chromophore
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III. Infrared Spectrometry
Radiation energy in the infrared region is absorbed by the
organic compound and converted into energy of molecular
vibration.
The energy absorption pattern thus obtained is commonly
referred to as an infrared spectrum which has the plot of
intensity of radiation absorption versus wavelength ofabsorption.
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Visible
Ultra
violet
Radio
Gamma
ray
EnergyWave
Number VWavelength
Frequency
TypeRadiation
Typespectroscopy
TypeQuantum Transition
Kcal/mol
Electronvolts,eV cm-1
cm Hz
9.4 x 107 4.9 x 106 3.3 x 1010 3 x 10-11 1021
9.4 x 103
4.9 x 102
3.3 x 106
3 x 10-7
1017
9.4 x 101 4.9 x 100 3.3 x 104 3 x 10-5 1015
9.4 x 10-1 4.9 x 10-2 3.3 x 102 3 x 10-3 1013
9.4 x 10-3 4.9 x 10-4 3.3 x 100 3 x 10-1 1011
9.4 x 10-7 4.9 x 10-8 3.3 x 10-4 3 x 103 107
X-ray
Infrared
Micro-
wave
Gamma ray
emission
X-ray
absorption,
emission
UV absorption
IR absorption
Microwave
absorption
Nuclear
magnetic
resonance
Nuclear
Electronic
(inner shell)
Molecular
vibration
Electronic
(outer shell)
Molecular
rotation
Magnetically
induced spin
states
Spectral Properties, Application and Interactions of Electromagnetic Radiation
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Some Molecular Vibrations
C C
O
O HH
H
H
Stretch
Unsymmetrical bend
Symmetrical bend
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Atom, Group, and Molecular Rotations
C C
O
O
HH
H
H
X
YZ
OH group rotation
H atom rotation COOH group rotation
CH3
group rotation
Molecular rotation
Center of gravity of themolecule is at the origin
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Infrared Spectrum
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Infrared Absorption and Functional Groups
3.4 m Alkane
6.0 m cis-Double Bond10.3 m trans-Double Bond5.8 m Carbonyl3.7 m Hydroxyl Stretching of Acid Group2.9 m Hydroxyl