Post on 01-Jan-2020
27/11/2013
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RAFA 2013 (Prague, 5 November 2013)
Vincent Baeten, Juan Antonio Fernández Pierna, Philippe Vermeulen, Pierre Dardenne
Département Valorisation des Productions Agricoles
Unité Qualité des Produits
Walloon Agricultural Research Centre
(CRA-W, Belgium)
v.baeten@cra.wallonie.be
BASICS OF INFRARED AND RAMAN SPECTROSCOPY
2nd RAFA workshop on : Infrared spectroscopy, Raman spectroscopy
and chemometrics for monitoring of food and feed products, lab-to-
the-sample
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RAFA 2013 (Prague, 5 November 2013)
Nickolay Lamm
Source : http://www.lesoir.be/
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RAFA 2013 (Prague, 5 November 2013)
- 1st generation
Example : Kjeldahl
chemical reaction + physical separation
- 2nd generation
Example : chromatography techniques
physical separation + physical detection
- 3rd generation
Example : spectrometer/sensor
physical detection + data treatment/chemometrics
Evolution of analytical solutions
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RAFA 2013 (Prague, 5 November 2013)
Pará, Brasil
(30/12/2012)
Look, a rainbow!
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RAFA 2013 (Prague, 5 November 2013)
Violet: 400 - 420 nm
Indigo: 420 - 440 nm
Blue: 440 - 490 nm
Green: 490 - 570 nm
Yellow: 570 - 585 nm
Orange: 585 - 620 nm
Red: 620 - 780 nm
The rainbaw colours … 7 … are you sure?
Source : wikipedia, http://teaching.shu.ac.uk/hwb/chemistry/tutorials (2012)
Wavelength (nm)
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RAFA 2013 (Prague, 5 November 2013)
Discovery of Near InfraRed Radiation
• 17 March 1800
• William Herschel,Astronomer Royal attemptsto find out the spectralregion responsible for heatformation in his telescope.
•The NIR is discovered.
•Philosophical Transactionsof the Royal Society 90:255-83
(Source : Ian Murray, 2012)
The electromagnetic spectrum …
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RAFA 2013 (Prague, 5 November 2013)
The electromagnetic spectrum …
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� Absorption occurs when energy from the radiative source is absorbed by the material. (e.g. infrared absorption, UV and DAD detectors)
� Reflection occurs when incident radiation is reflected by a material. (i.e. internal reflection)
� Emission occurs when radiative energy is released by the material. (e.g. Fluorescence, fluorescence detector)
� Elastic scattering occurs when incident radiation is scattered by a material. (e.g. Rayleight scattering, ELSD detector)
� Inelastic scattering occurs when the is an exchange of energy between the radiation and the matter that shifts the wavelength of the scattered radiation. (e.g. Raman scattering)
� … (Coherent, resonance, impedance, …)
Nature of the interation of radiation with
materials (molecules)
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Greenglass
Internal
reflected ray
Transmitted ray
red-blue
attenuated(Source : Ian Murray, 2012)
Nature of the
interation of
radiation with
materials
(molecules)
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RAFA 2013 (Prague, 5 November 2013)
Greenglass
i i
r
reflection refraction dispersion absorption
r
iRI
sin
sin=
Aλ = log1/T ∝ conc*path
(Source : Ian Murray, 2012)
Nature of the interation of radiation with materials (molecules)
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RAFA 2013 (Prague, 5 November 2013)
groundgreenglass
Indicatrix of diffuse+specularreflected light
scattering
No lightAλ= log1/R ∝ conc*path
(Source : Ian Murray, 2012)
Nature of the interation of radiation with materials (molecules)
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RAFA 2013 (Prague, 5 November 2013)
Ia
I0
Ir
ABSORBANCE oABSORBANCE or optical densityr optical density
====
R
1LogA
REFLECTANCEREFLECTANCE IrR=
I0Opaque samplesPowdersNIR & MIR (Raman)
TRANSMITANCETRANSMITANCE ItT=
I0Clear samplesGases, liquidsNIR & MIR (Raman)
Ia
I0
It
====
T
1LogA
ABSORBANCE ABSORBANCE or or opticaloptical densitydensity
Mode of measure of spectra
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• If vibration changes the dipole moment then bond can absorb photons
• A photon of exactly the right frequency is absorbed & excites the bond to a higher vibrational state
• Frequency = qualitative analysis:IDENTITY
• Amplitude = quantitative analysis:AMOUNT
C H
• Covalent bonds share electrons between atoms in a molecule
E=hν
1.09 Å
• Bonds have length, strength & direction unique to each pair of atoms
• Bonds act like springs joining atoms
• Bonds vibrate at unique frequencies due to atomic masses & ‘stiffness’
C H
+_
(Source : Ian Murray, 2012)
Nature of the covalent bond
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RAFA 2013 (Prague, 5 November 2013)
(So
urc
e : I
an M
urr
ay, 2
012)
Potential energy associated to a molecule
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RAFA 2013 (Prague, 5 November 2013)
UV VIS IR Microwave Radio
Frequency
Wavelength (nm)
Wavenumber (cm-1)
800 2500
4000 400
� Near-infrared spectroscopy
(NIR)
� Mid-infrared spectroscopy
(MIR)
Fundamental vibrationsOvertone and
combination vibrations
∂ µ /∂q ≠ 0 ∂ µ /∂q ≠ 0
12500
25000
Energy
The electromagnetic spectrum …
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RAFA 2013 (Prague, 5 November 2013)
• Organic compound exposed to electromagnetic radiation, can absorb energy of only certain wavelengths (unit of energy)– Transmits or scatters energy at other wavelengths
• Changing frequencies to determine which are absorbed and which are transmitted produces an absorption spectrum
• Energy absorbed is distributed internally in a distinct and reproducible way
Mid-infrared (MIR/IR) spectroscopy - theory
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An example of near infrared (NIR) spectra
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0,3
0,8
1,3
1,8
1.100 1.300 1.500 1.700 1.900 2.100 2.300 2.500A
bso
rba
nce
(Lo
g 1
/R)
Wavelength (nm)
Wheat (15.8 %)
Wheat (21.3 %)
Water (100 %)
NIR spectra : main spectral bands
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RAFA 2013 (Prague, 5 November 2013)
0
0,5
1
1,5
2
1.100 1.300 1.500 1.700 1.900 2.100 2.300 2.500
Ab
sorb
an
ce (
Log
1/R
)
Wavelength (nm)
Honey (Rapeseed)
Saccharose
Water
NIR spetra : honey spectrum
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RAFA 2013 (Prague, 5 November 2013)
0
0,1
0,2
0,3
0,4
05001.0001.5002.0002.5003.0003.5004.000
Ab
sorb
an
ce (
Log
1/R
)
Wavenumber (cm-1)
Mid-IR
Mid-IR
Example of mid infrared (IR, MIR) spectra
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Raman theory : Raman effect
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1
3
hνν νν
RA
Y
hνν νν
R(S
t)
hνν νν
R(a
St)
2
1
0
E
1st
electronic
excited state
Virtual
states
Ground
electronic state
hνν νν 0
hνν νν 0
hνν νν 0
hνν νν I
R
Figure : Energy level diagram showing the basic transitions involved in
infrared, Rayleigh & Raman effects. (Adapted from Nakamoto, 1986;
Baranska, 1987 and Bulkin, 1991)
Raman scattering
Raman theory : Raman effect
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Raman scattering
� Origin = same type of vibrations as infrared spectroscopy
� Appears when a molecule irradiated with a monchromatic light
– some photons scattered at same frequency (Rayleigh scattering)
– some photons scattered at different frequencies (Raman scattering)
– Rayleigh scattering frequency – Raman scattering frequen cy = corresponds to energy of vibrational transition
� Some characteristics : any monochromatic light can be used, Raman effect is instantaneous (vibrational absorption is fast but slower thanRaman)
Raman theory : Raman effect
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RAFA 2013 (Prague, 5 November 2013)
0
0,1
0,2
0,3
0,4
0,5
0,60
0,1
0,2
0,3
0,4
0,5
0,6
0 500 1.000 1.500 2.000 2.500 3.000 3.500 4.000
Ab
sorb
an
ce (
Log
1/R
)
Wavenumber (cm-1)
Mid-IR
Raman
Sca
tte
rin
g i
nte
nsi
ty
Example of mid infrared (NIR) and Raman spectra
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Mathematical
model+
Data-base
Reference
values
Spectrum
Mathematical
modelPredicted
values+
Quantitative analysis
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RAFA 2013 (Prague, 5 November 2013)
Feed & Feed ingredients
Large spectroscopic and microscopic data-bases
Merging data-bases :
CRA-W (BE) & AUNIR
(UK) data-bases
Network of Network of
instruments instruments
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RAFA 2013 (Prague, 5 November 2013)
Quality control for different companies
- Cereals based companies (e.g. flour, bread or beer
producers)
- Reception stage - During the production stages (on-line)- Final products
- Bioethanol companies
- Screening tool to optimize the segregation of raw material - Track the fermentation and conversion - Rapid analysis of by-products
- Breeding programs
- Unique tool that allow the analysis of the cereals in the field
- Able to handle the huge number of samples
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RAFA 2013 (Prague, 5 November 2013)
Norm : example
for seeds and
kernels (Cereals,
Oil seeds, …)
EN 15048
“Cereals - moisture
and protein -
Near-Infrared-Spectr
oscopy in whole
kernels”
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RAFA 2013 (Prague, 5 November 2013)
See FEED module of the course
Norm : example
for seeds and
kernels (Cereals,
Oil seeds, …)
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RAFA 2013 (Prague, 5 November 2013)
Wavelengthselector
Sample
Wavelengthselector
Detector
Source
Source Sample
Detector
Detector
a) Transmission mode
b) Reflection mode
Polychromatic radiation
Polychromatic radiation
Wavelength (nm)
NIR spectrum
Spectroscopy : instrumentation
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RAFA 2013 (Prague, 5 November 2013)
Dispersive instruments (NIR, MIR & Raman)
(Williams and Norris, 2001)32
RAFA 2013 (Prague, 5 November 2013)
Dispersive NIR instruments
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RAFA 2013 (Prague, 5 November 2013)
Fourier Transform (FT) NIR instruments
(NIR, MIR & Raman)
(Williams and Norris, 2001)
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RAFA 2013 (Prague, 5 November 2013)
Fourier Transform (FT) NIR instruments
(NIR, MIR & Raman)
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RAFA 2013 (Prague, 5 November 2013)
http://www.perkinelmer.com/
Fourier Transform (FT) NIR instruments
(NIR, MIR & Raman)
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RAFA 2013 (Prague, 5 November 2013)
Fourier Transform (FT) NIR instruments
(NIR, MIR & Raman)
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RAFA 2013 (Prague, 5 November 2013)
Fourier Transform (FT) NIR instruments
(NIR, MIR & Raman)
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RAFA 2013 (Prague, 5 November 2013)
200-1100 nm1100-2500 nm
STATIONARY GRATING
Diode array instruments
Data treatment
sabs
λ
InGaAs detector
128 diodes
GratingSource
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Diode array instruments
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RAFA 2013 (Prague, 5 November 2013)
Step3
Step4
Step5
Step1
Step2
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RAFA 2013 (Prague, 5 November 2013)
At-line, on-line & in-line instruments
Sébastien Gofflot, CRA-W
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RAFA 2013 (Prague, 5 November 2013)
Source : Kaiser
optical systems
www.kosi.com
Ethanol bio-transformation – on-line Raman
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RAFA 2013 (Prague, 5 November 2013)
Schematic of the n-around-1 fiber-optic probe.
(Mc Creery, 2000)
At-line, on-line & in-line instruments
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RAFA 2013 (Prague, 5 November 2013)
http://www.perkinelmer.com
At-line, on-line & in-line instruments
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RAFA 2013 (Prague, 5 November 2013)
At-line, on-line & in-line instruments
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RAFA 2013 (Prague, 5 November 2013)
NIR
GPS
Field application
Dr Georges Sinnaeve, CRA-W
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RAFA 2013 (Prague, 5 November 2013)
0 200 m100100
Protein (% DM)
11.25-11.5011.51-11.7511.76-12.0012.01-12.2512.26-12.5012.51-12.7512.76-13.0013.01-13.2513.26-13.50
Dr Georges Sinnaeve, CRA-W
Field application
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And more instruments …
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TruScan* Handheld Raman for Material Identification
http://www.thermoscientific.com
And more instruments …
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RAFA 2013 (Prague, 5 November 2013)
Intensity information
(i.e. absorbance)
Frequency information
(i.e. wavelengths)
Spatial information
And more instruments …
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At your service …
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RAFA 2013 (Prague, 5 November 2013)
A team at your service
Dr Vincent Baeten Mrs Claudine Clement
Dr Juan A. Fernández Pierna Mrs Anne Mouteau
Ir Philippe Vermeulen Ms Sandrine Mauro
Ing Bernard Lecler Ms Emma Mukandoli
Dr Ouissam Abbas Mr Marie Collard
Dr Pascal Veys Mr Nicolas Crasset
Dr Marie-Caroline Lecrenier Ms Marianne Flahaut
Ing Olivier Minet Mr Quentin Arnould
Ir Quentin Ledoux Mr Benoît Scaut
Mr Alexandre Quoitot Mr Nicaise Kayoka Mukendi
Ir Damien Vincke Mr Stéphane Brichard
Dr Pierre Dardenne (Head of the Department)
Dr Georges Sinnaeve, Ir Frédéric Dehareng, Ir Clément Grelet (U14)
Dr Gilbert Berben, Dr Olivier Fumière (U16)