Upload
others
View
19
Download
0
Embed Size (px)
Citation preview
© 2019 HORIBA, Ltd. All rights reserved. 2© 2019 HORIBA, Ltd. All rights reserved. 2
Raman Spectroscopy with Practical Applications
David Tuschel
May 29, 2019
© 2019 HORIBA, Ltd. All rights reserved. 3
Raman spectroscopy and photoluminescence Polymorphism Liquid and head space Raman spectroscopy Raman spectroscopy of polymers Particle size characterization with chemical
identification
Presentation Topics
© 2019 HORIBA, Ltd. All rights reserved. 4
Vibrational spectroscopy studies vibrations in a system using light. IR and Raman spectroscopy are the most common and
complementary to each other. IR spectroscopy is absorption (or reflection) spectroscopy Raman spectroscopy is scattering spectroscopy
Applications of vibrational spectroscopy Molecular spectroscopy
- Vibrations of atoms within molecules- Gas, liquid and solid
Solid state and material science- Vibrations of atoms within molecules (e.g. molecular crystals, amorphous
materials)- Vibrations between atoms and molecules (e.g. amorphous materials)- Vibrations of crystalline lattice- From liquid to solid (e.g. gel, crystal)
Vibrational Spectroscopy
© 2019 HORIBA, Ltd. All rights reserved. 5
Raman Scattering
RayleighStokes Anti-Stokes
E0
E1
Virtual States
v0
v1
v2
v3
hνex
hνex hνex hνex
h(νex – νv)h(νex + νv)
© 2019 HORIBA, Ltd. All rights reserved. 6
Raman Spectra of Polystyrene at 532, 638 and 785 nm Excitation
Raman Shift (cm-1)
Inte
nsity
/ A
rbitr
ary
Uni
ts
λex: 532 nm
λex: 638 nm
λex: 785 nm
© 2019 HORIBA, Ltd. All rights reserved. 7
Raman Spectra of Polystyrene at 532, 638 and 785 nm Excitation
Wavelength (nm)
Inte
nsity
/ A
rbitr
ary
Uni
ts
λex: 532 nm
λex: 638 nm
λex: 785 nm
© 2019 HORIBA, Ltd. All rights reserved. 8
Raman Spectra of Glass Microscope Slide at 532, 638 and 785 nm Excitation
Raman Shift (cm-1)
Inte
nsity
/ A
rbitr
ary
Uni
ts
Photoluminescence
PhotoluminescenceRaman Scattering
λex: 532 nm
λex: 638 nm
λex: 785 nm
© 2019 HORIBA, Ltd. All rights reserved. 9
Raman Spectra of Fused Quartz at 532, 638 and 785 nm Excitation
Raman Shift (cm-1)
Inte
nsity
/ A
rbitr
ary
Uni
ts
λex: 532 nm
λex: 638 nm
λex: 785 nm
© 2019 HORIBA, Ltd. All rights reserved. 10
Photoluminescence of Few-Layer MoS2
Wavelength (nm)
Inte
nsity
(arb
itrar
y un
its)
691
Raman bands
930λex: 633 nm
λex: 532 nm
Same location
© 2019 HORIBA, Ltd. All rights reserved. 11
Raman Spectra of Al2O3:Cr at 532 and 633 nm Excitation
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
144 417
568
734
λex: 532 nm
λex: 633 nm
PL
PL
© 2019 HORIBA, Ltd. All rights reserved. 12
Photoluminescence Spectra of Al2O3:Cr at 405, 532 and 633 nm Excitation
Wavelength (nm)
Inte
nsity
(Arb
itrar
y U
nits
)
810
λex: 532 nm
λex: 633 nm
λex: 405 nm
692.8 694.2R1R2
© 2019 HORIBA, Ltd. All rights reserved. 13
Raman Spectra of Methanol and Ethanol
20000
15000
10000
5000
0
500 1000 1500 2000 2500 3000 3500
OHstretching
CHstretching
CO stretching
CH3deformation
Raman Shift (cm-1)
Ram
an In
tens
ity (a
rbitr
ary
unit) CO
stretching
CH3 and CH2deformation
13
© 2019 HORIBA, Ltd. All rights reserved. 14
Spectral Analysis: Comparison
The same chemical composition C6H12O6but different molecular structures
Inte
nsity
(a.u
)
1 000 2 000 3 000Wavnumbers (cm-1)
glucose
fructose
© 2019 HORIBA, Ltd. All rights reserved. 15
Similar Molecular Structures3,4-Methylenedioxymethamphetamine (MDMA) Methamphetamine
500 1000 1500 2000 2500 3000 3500Raman Shift (cm-1)
Ram
an Intensity (arbitrary unit)
© 2019 HORIBA, Ltd. All rights reserved. 16
DiastereomersPseudoephedrineEphedrine
500 1000 1500 2000 2500 3000 3500Raman Shift (cm-1)
Ram
an Intensity (arbitrary unit)
© 2019 HORIBA, Ltd. All rights reserved. 17
1000
800
600
400
200
Inte
nsity
(cou
nts/
s)
Wavenumber (cm-1)
MgSO4
Substitution
Na2SO4
© 2019 HORIBA, Ltd. All rights reserved. 18
Carbon Nanotubes
200
400
600
800
1 000
1 200
1 400
1 600
1 800
2 000
2 200
2 400
2 600
2 800
3 000
Inte
nsity
(cnt
)
200 400 600 800 1 000 1 200 1 400 1 600 1 800 2 000Raman Shift (cm-1)
Radial breathing mode (RBM) Nanotube diameter
Tangential modes (G band) Electronic properties
D band Info on defects
© 2019 HORIBA, Ltd. All rights reserved. 19
Raman Spectroscopy and Polymorphism
Monoclinic and Tetragonal ZrO2
Anatase and Rutile TiO2
Acetaminophen Forms I and II
© 2019 HORIBA, Ltd. All rights reserved. 20
200
300
400
500
600
700
Inte
nsity
(cnt
/sec
)
200 300 400 500 600 700 800 900 1 000
MZrO2TZrO2
635
.9
177
.7 1
90.2
221
.2
265
.7
306
.0 3
32.9
346
.3
380
.5
475
.6 5
02.5
536
.6 5
57.3
613
.2
642
.1
145
.7
176
.7 1
88.1
261
.5
322
.5
465
.3
608
.0
At ambient conditions the monoclinic phase is stable. The high T tetragonal phasecan be stabilized by alloying with oxides such as Y2O3, Al2O3, CaO. There is a thirdphase which is cubic, and stable at even higher temperatures.
ZrO2 : Monoclinic and Tetragonal
Tetragonal
Monoclinic
© 2019 HORIBA, Ltd. All rights reserved. 21
Anatase and Rutile TiO2 with 532 nm Excitation
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
516
445610
397197
143
241
638
Rutile
Anatase
Both Anatase and Rutile are TiO2 but of different polymorphic forms - identical chemical composition, different crystalline structures.
© 2019 HORIBA, Ltd. All rights reserved. 22
Rutile with Anatase TiO2 Impurity, Green Spectrum
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
516
445 610
397197
143
241638
Rutile
Anatase
© 2019 HORIBA, Ltd. All rights reserved. 23
Acetaminophen Form I (Red) and Form II (Blue)
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
Form I
Form II
© 2019 HORIBA, Ltd. All rights reserved. 24
Acetaminophen Form I (Red) and Form II (Blue)
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
1447
1324
1619
1649
1221
1169
1237
1561
1279 1611Form I
Form II
1258 1372
11691245
1265
1327
13751452 1508
1576
16091625
1650
© 2019 HORIBA, Ltd. All rights reserved. 25
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
505413
466
652
332
330
340628
392605
Form I
Form II
345389
394
419454
508
651
624
605
Acetaminophen Form I (Red) and Form II (Blue)
© 2019 HORIBA, Ltd. All rights reserved. 26
Raman Shift (cm-1)
Inte
nsity
(Arb
itrar
y U
nits
)
215
90
109
51
25
3342
152
56
130
Form I
Form II45
76122
140
206
Acetaminophen Form I (Red) and Form II (Blue)
© 2019 HORIBA, Ltd. All rights reserved. 27
Liquid and Head Space Raman Spectroscopy
Hydrogen Bonding and Molecular Interactions
© 2019 HORIBA, Ltd. All rights reserved. 28
Macro-Raman Sampling from a Cuvette
© 2019 HORIBA, Ltd. All rights reserved. 29
Macro-Raman Sampling from a Bottle
© 2019 HORIBA, Ltd. All rights reserved. 30
Head Space of Beer – CO2
Raman Shift / cm-1
Inte
nsity
/ co
unts
Head Space
1408.8
1284.8
O2
1387.5
1264.4
fwhm: 0.9 cm-1
1369.3
ν1
2ν2
2ν21 hotν1
1/ν1(13C)
2ν2(13C)
ν1 should be at 1330 cm-1
2ν2 should be at 1334 cm-1
Fermi splitting = 103 cm-1
© 2019 HORIBA, Ltd. All rights reserved. 31
Sparkling Water – CO2
Raman Shift / cm-1
Inte
nsity
/ ar
bitr
ary
units
Head Space
Liquid
1633.6
1379.6
1285.0
O2
1387.7
1272.7
fwhm: 0.9 cm-1
fwhm: 9.9 cm-1
© 2019 HORIBA, Ltd. All rights reserved. 32
Ammonia – Hydrogen Bonding
Raman Shift / cm-1
Inte
nsity
/ ar
bitr
ary
units
Head Space
Liquid3424O-H
3314N-H
3340N-H
3659O-H
Note the relative strengths of hydrogen bonding between NH3 and H20.
© 2019 HORIBA, Ltd. All rights reserved. 33
Methanol – Hydrogen Bonding
Raman Shift / cm-1
Inte
nsity
/ ar
bitr
ary
units
Head Space
Liquid
2832 2941
3340O-H
3684, 3697O-H
28462956
© 2019 HORIBA, Ltd. All rights reserved. 34
Raman Spectroscopy of Polymers
Aromatic PolymersPET
Stretched Polypropylene
© 2019 HORIBA, Ltd. All rights reserved. 35
Polymers• Very long chain of (usually) organic repeating unit. Extensive flexibility is
possible:– Non-oriented “spaghetti” form (amorphous), or oriented chains, as a
result of extrusion, which can be amorphous or crystalline– Orientation is a requirement for crystallinity (but not visa versa)– Often there are lamellae, regions where the chains fold back and forth
over each other
© 2019 HORIBA, Ltd. All rights reserved. 36
Raman Characterization of Polymers
• Types of Information– Chemical Identification– Tacticity (side group positioning)– Morphology
• Orientation• Crystallinity
• Applications– Contaminant ID– Composition of copolymer or blend– Engineering strength, elasticity, dyeability, etc.– Drug delivery (API solvent)– Barrier films (food, biomedical, etc.)
© 2019 HORIBA, Ltd. All rights reserved. 37
Raman Spectra of Aromatic PolymersThe strong band near 1000 cm-1 that is characteristic of a ring mode in PS is never observed in any aromatic with 1,4 substitutions on the ring, as in Kevlar and PET.
x10 3
0
5
10
15
20
25
30
35
40
45
500 1 000 1 500 2 000 2 500 3 000 3 500Raman Shift (cm-1)
Kevlar
PET
Polystyrene
Aromatic CH stretches
Saturated CH stretches
Carbonyl band
Aromatic band
Amide band
Aromatic band
© 2019 HORIBA, Ltd. All rights reserved. 38
Raman Studies of PET: Polarization and Crystallinity
C=O stretchingWidth=>crystallinity
glycol modes:Indicators of conformation
Raman Shift / cm-1
Inte
nsity
/ ar
bitr
ary
units
© 2019 HORIBA, Ltd. All rights reserved. 39
Raman Shift (cm-1)
Inte
nsity
(Cou
nts) 835
Unperturbed
Stretched
315
992
Stretched and Unperturbed Polypropylene
© 2019 HORIBA, Ltd. All rights reserved. 40
Raman Shift (cm-1)
Inte
nsity
(Cou
nts)
169
315
Unperturbed
Stretched
522
449
Stretched and Unperturbed Polypropylene
393391
© 2019 HORIBA, Ltd. All rights reserved. 41
Raman Shift (cm-1)
Inte
nsity
(Cou
nts)
803835
Unperturbed
Stretched836
968
Stretched and Unperturbed Polypropylene
992 993
© 2019 HORIBA, Ltd. All rights reserved. 42
Raman Shift (cm-1)
Inte
nsity
(Cou
nts)
11461148
Unperturbed
Stretched
1213
1325
Stretched and Unperturbed Polypropylene
1324
1354 14311430
1454
© 2019 HORIBA, Ltd. All rights reserved. 43
Introducing ParticleFinder• ParticleFinder offers
automated – Particle location on
optical images– Particle size/shape
characterization– Particle analysis using
Raman spectroscopy– Particle chemical
identification
• ParticleFinder includes:– Morphological analysis
• Thresholding• Morphological filtering• Size and shape
parameters– Chemical analysis
• Automated Raman acquisition
• Fast analysis with high throughput systems
• Flexible capabilities* for different sample types
– Multiple laser wavelengths (UV, visible, NIR)
– High spectral resolution– Ultra-low frequency
© 2019 HORIBA, Ltd. All rights reserved. 44
Step-by-Step
Acquire video
Single image, or montagedwide field of view image
Threshold
Locate dark particles on bright background, or
bright particles on dark background
Process
Erode/dilate/open/ close/majority, fill holes,
remove edge particles
© 2019 HORIBA, Ltd. All rights reserved. 45
Characterize
Position, size, shape
Acquire Raman
Automatically analyze each particle
Select
Screen particles based on position, size or shape
Step-by-Step
© 2019 HORIBA, Ltd. All rights reserved. 46
Application Example• Pharmaceutical crystals on glass slide• 1 × 1 mm2 area imaged with video montage (12
images)• Image thresholds locate 44 particles
– Exclude edge particles– Exclude particles with area < 50 μm2
STATISTICS (mean)DIAMETER 19.7 μmPERIMETER 109.7 µm AREA 386.0 µm2
MAJOR AXIS 33.6 μmMINOR AXIS 14.8 μmELLIPSE RATIO 0.50CIRCULARITY 0.64
Video image
Binary image
© 2019 HORIBA, Ltd. All rights reserved. 47
ParticleFinder Workspace – Paracetamol and PMMA
© 2019 HORIBA, Ltd. All rights reserved. 48
ParticleFinder Tabulated Results
© 2019 HORIBA, Ltd. All rights reserved. 49
Raman spectroscopy and laser excited photoluminescence can be performed using the same instrument.
Raman spectroscopy can be used to differentiate polymorphs and characterize polymers.
Vapor phase and liquid molecular interactions are manifest in Raman spectra.
Particle size characterization with chemical specificity
Conclusions
© 2019 HORIBA, Ltd. All rights reserved. 50© 2019 HORIBA, Ltd. All rights reserved. 50