Výběr z aplikací infračervené

The Leader in Spectroscopy

Výběr z aplikací infračervené spektrometrie

Ján Pásztor, Nicolet CZ s.r.o.


Fourier Transform Infrared Spectroscopy

• IntroductionElectromagnetic radiation

Vibrational spectroscopy

• Instrumentation Interferometry

The Fourier Transform


10 10 10 10 10 10 10 109 7 5 3 1 -1 -3 -5

Wavenumbers

x-rays

ultraviolet

visible

near-IR

mid -IR

far-IR

microwave

radio waves

Wavelength in microns

nuclear electronic vibrational

10 10 10 10 10 10 10 10

transitions

-5 -3 -1 1 3 5 7 9

rotational

Electromagnetic Spectrum


Harmonic Vibrations

• The vibration of a diatomic molecule can be approximated by the vibration of a spring

• The wavenumber of the vibration equals:

with m=

1

2x

c

k

m1m2

m1 + m2

m

RRee--DDRR RRee RRee++DDRR


Quantized harmonic, anharmonic

hh/2/2pp ((k/k/M).(M).(νν+1/2)+1/2)


Selection Rules for Infrared Activity

• The frequency of the light must be identical to the frequency of the vibration (resonance)

• The dipole of the molecule must change during the vibration

• The direction of the dipole change must be the same as the direction of the electric field vector


Cl H N N

Dipole Change

• To absorb energy, the dipole must change when the transition occurs

• The intensity of the absorption is proportional to the magnitude of the dipole change


C CC C

Stretching Deformation

Bending Twisting

C

+ -

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

%T

1000 1500 2000 2500 3000 3500 4000

cm-1

Molecular Vibrations


1000 1500 2000 2500 3000 3500

Wavenumbers (cm-1)

Fingerprint region

Functional groups

Polyatomic Molecules

• The spectrum becomes more complex as the number of bonds increases


Non-linear Triatomic Molecule (H2O)

• 3 normal vibrations (3N-6)

• Coupling of vibrations bendingbending

(1595 cm(1595 cm--11))

symmetricsymmetric

stretchingstretching

(3657 cm(3657 cm--11))

asymmetricasymmetric

stretchingstretching

(3756 cm(3756 cm--11))

E1

E2

E E

En

erg

y

Fre

qu

en

cy


Fixed Rotations in a Lattice (-CH2)

scissoringscissoring

(~1463 cm(~1463 cm--11))

twistingtwisting

(~1300 cm(~1300 cm--11))

waggingwagging

(~1280 cm(~1280 cm--11))

+ +

+-

CHCH22 rocking at 720 cmrocking at 720 cm--11

• Since the atoms are fixed in a skeleton, more bending vibrations occur


Overtones

Occur close to INTEGER

MULTIPLES Of FUNDAMENTAL Bands.

For example: C-H Overtones Will Occur Near:

First Overtone

2960 cm-1 (C-H Stretch) * 2 = 5920 cm-1

Second Overtone

2960 cm-1 (C-H Stretch) * 3 = 8880 cm-1

The intensity of the absorption depends on the degree of

anharmonicity and gets weaker with increasing overtones


Combination Bands

COMBINATION Bands Appear Near The Sum Of

Two Or Three FUNDAMENTAL Bands

For Example: A C-H Combination Will Occur Near…

2960 cm-1 (C-H Stretch) + 1460 cm-1 (C-H Bend)

= 4420 cm-1


NIR spectrum

-0.3

-0.2

-0.1

0

0.1

0.2

0.3

0.4

0.5

700 900 1100 1300 1500 1700 1900 2100 2300 2500

Wavelength (nm)

Ab

so

rban

ce (

Lo

g 1

/R)

Combination

1st Overtone

2nd Overtone

3rd Overtone


Sources, Beamsplitters and Detectors


Source, Beamsplitter, and Detector Combinations Depend on Application


FT-IR System


+ =

+ =

Wave Interactions (Interference)

• In-phase Constructive

interference

• Out-of-phase Destructive

interference


DetectorDetector

Michelson Interferometer-1

Fixed mirrorFixed mirror

l 0 -l

InterferometerInterferometer

Moving mirrorMoving mirror

IR IR

SourceSource

BeamsplitterBeamsplitterBM

Path difference = 0

BMBF =

BF



Detector

Fixed mirrorFixed mirrorInterferometerInterferometer


l 0 -l

IR IR

SourceSource

BeamsplitterBeamsplitterBM

Path difference = 1/4

BM - 1/8 BF =

BF

DetectorDetector




DetectorDetector



l 0 -l

IR IR

SourceSource

BeamsplitterBeamsplitter

Path difference = 1/2

BM - 1/4 BF =

BM

BF



BeamsplitterBeamsplitter 0 0 --

DetectorDetector


IR IR

SourceSource




Path difference

Signal at the Detector

Vo

lta

ge

0 1/4 1/2 3/4


The Interferogram

One Wavelength Many Wavelengths

020406080100120140

-1.0

-0.5

0.0

0.5

1.0

010002000300040005000

-3

-2

-1

0

1

2

3

4

Data Points Data Points

Vo

lts

Vo

lts


Sampling the Interferogram

Source

He-Ne laser


Dynamic Alignment

Fixed mirror

x 0 -x

Beamsplitter

Laser diodes

He-Ne laserMoving mirror

XYR


Dynamic Alignment Advantages

• Better short term stability

• Better long term stability

• Better spectral line shapes


5001000150020002500300035004000

5

10

15

20

25

30

35

40

Wavenumbers

Fast Fourier Transformation

FFT

010002000300040005000

-3

-2

-1

0

1

2

3

4

Data Points

V

o

l

t

s

Interferogram Spectrum

E

m

i

s

s

i

v

i

t

y


Transmission Spectrum

170018001900210022002300

-3

-2

-1

0

1

2

3

4

Data Points

Vo

lts

170018001900210022002300

-3

-2

-1

0

1

2

3

4

Data Points

Vo

lts

5001000150020002500300035004000

5

10

15

20

25

30

35

40

Wavenumbers

Em

issiv

ity

5001000150020002500300035004000

5

10

15

20

25

30

35

40

WavenumbersE

mis

siv

ity

bkg: FFT

sam: FFT

5001000150020002500300035004000

20

30

40

50

60

70

80

90

Wavenumbers

Tra

nsm

itta

nce

Ratio


Summary

Advantages of FT-IR Instruments

• Multiplex advantage (Felgett’s) All wavelengths are measured simultaneously

• Throughput advantage (Jacquinot’s) Higher energy throughput (larger apertures)

• Precision advantage (Connes’) Internal calibration is derived from He-Ne laser (precision = 0.01 cm-1)


Technique Choice

• Analytical goals Quantitative

Qualitative

• Sample dependent factors Size

Chemical makeup of sample

• Optimization


Sampling Techniques and Applications

• Transmission

• Attenuated Total Reflectance - ATR

• Diffuse Reflectance – DRIFTS

• Gas Analysis

• Semiconductor

• Oil Analysis

• GC/FT-IR

• TGA/FT-IR

• Mobile/Portable FT-IR


Advances in Accessory Design

• Automatic set-up of system parameters and experiment

• Rugged, permanently aligned, plug & play design

• On-line help and tutorials

• Design for fast purge

• Operation integrated with spectrometer and software

• Automatic tests ensure proper accessory operation

• System checks ensure high quality spectra are collected


Transmission Analysis

• Requires sample preparation

• Proper pathlength required Strong absorbers - short pathlength

Weak absorbers - long pathlength

• Solids, liquids, gases

• Qualitative analysis

• Quantitative analysis

• Maximum sensitivity

• Low cost


The peak at 3651 cm-1

was used to quantify the

antioxidant butylated hydroxy

toluene (BHT) in the poly-a-olefin

(PAO) lubricant

Analysis of Antioxidant Levels in Lubricating Oil


Attenuated Total Reflectance

• Versatile and non-destructive technique for infrared sampling

• Requires minimal or no sample preparation

• Useful for surface characterization


Considerations for ATR Analysis

• Refractive index of ATR and sample

• Pathlength requirements

• Spectral range of interest

• Phase of sample: solid, liquid, gel

• Chemical properties

• Hardness of sample

d p =

2p natr (sin2 q) -nsample

natr( )2[ ] 1/2


Attenuated Total Reflectance ATRSingle Bounce vs Multi-bounce

• Small sampling area

• Use for strong absorbers

• Solid samples

• Broad sampling area provides

greater contact with the sample

• Use for weak absorbers or dilute

solutions

ZnSe Internal Reflection Element

Penetration depth

up to two micronsPlunger

Crystal Cap

IR Beam

Crystal


Properties of ATR Crystals

Material

ATR Spectral

Range (cm-1)

Refractive

Index

Depth of Penetration (µ)

(at 45º & 1000 cm-1) Uses

Germanium 5,500 - 675 4 0.66

Good for most samples.

Strong absorbing

samples, such as dark

polymers.

Silicon8,900 - 1,500 &

360-1203.4 0.85

Resistant to basic

solutions.

AMTIR 11,000 - 725 2.5 1.77Very resistant to acidic

solutions.

ZnSe 15,000 - 650 2.4 2.01 General use.

Diamond 30,000 - 200 2.4 2.01

Good for most samples.

Extremely caustic or hard

samples.


Analysis of Fibers Using Single Bounce ATR

• No sample preparation

• Non-destructiveto the sample

• Shallow depthof penetrationgood for dark polymers


Identifying Fiber Threads Inside An Automotive Hose


ATR Summary

• Ease-of-use

• Rapid qualitative and quantitative analysis


• Multiple crystals for various sampling needs

• Best technique for condensed phase samples


Diffuse Reflectance (DRIFTS)

• A multi-modal technique Specular Reflectance

Diffuse Specular Reflectance

“True” Diffuse Reflectance

• Kubelka-Munk equation Absorbance-like results

R = reflectance with infinite depth

K = molar absorption

S = scattering coefficient

F(R) = (1-R)2

2R =

KS


Compound Parabolic Concentrator

• Independent of sample height

• Reduces sample packing effects

• Minimizes front surface reflection (specular component)

• Efficient high throughput collection optics

• Sample positioned below optics

• No damage to optics from sample spills

Input / output optics

CPC

Powder sample cup

CPC Design


DRIFTS Analysis of Pharmaceutical Powders


DRIFTS Analysis of Pharmaceutical Powders

Analytical Goal

• Simplified sample preparation

• Identification of key ingredients

Ibup ro fen Powder

0.3

0.4

0.5

Lo

g(1

/R)

Nap roxen Sodium Powder

0.2

0.4

0.6

Lo

g(1

/R)

Ps eudoephedrine H Cl Powder

0.50

0.55

0.60

0.65

0.70

0.75

Lo

g(1

/R)

600 800 1000 1200 1400 1600 1800

Wav enumbers (cm-1)


Benefits of Diffuse Reflectance

• Good choice for dilute powders

• Analysis of non-reflective materials

• Minimal sample preparation


FT-IR Gas Analyzer

• Detects pollutants CO, NOx, HC

NH3, HCN, N2O

• Nexus Gas Analyzer 2 meter gas cell

MCT-A detector

• Detection limits – less than 1 ppm

• 0.09 cm-1 resolution


NOx Reduction in Diesel Exhaust

• Diesel engines are run “lean,” i.e. with excess air during combustion

• “Naturally” low hydrocarbon and CO emissions but high NO and NO2

emissions

• “Urea” with catalyst can reduce NO and NO2

• However, concern is that HCN is generated


HCN Emissions

• “Urea” injection reduced NO and NO2 and can be tuned to minimize HCN generation

Abs

HCN 97 ppm in exhaustHCN 0.6 ppm in exhaustHCN standard

-0.2

-0.0

0.2

0.4

0.6

0.8

1.0

3250 33003350cm-1


Semiconductor Wafer Analysis

• Semiconductor devices are manufactured on silicon wafers, using successive layers of metals and insulators

• Many devices are produced from each wafer. As many as 300 PentiumTM like devices, or more than 800 memory chips, can be produced from a single 8” or 12” diameter wafer


Semiconductor Analysis

• The samples were analyzed using the Nicolet® ECO 3000

• Samples were scanned in transmission (silicon is transparent to infrared radiation)


Si-H Variation


Conclusion

• Hydrogen concentration can effect the dielectric constant in these films

• Customer was able to identify a heating problem with the wafer platen in the deposition system, based on the shape of the center region of the profile

• After adjusting the temperature parameters in the system, uniform films were produced and device yields reached 98%


Approaches for Lubricant QCTotal Process Checking

• Incoming ingredient testing Base oil and add-pack lot consistency

• Blended product analysis Additive levels

• Outgoing product verification Assure product correct for shipment

• Used Oil Analysis Engine Monitoring

• Edible Oil Analysis Product Consistency


Integra Oil Analysis


Spectral Regions of Interest for Used Oil

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Absorbance

1000 1500 2000 2000 3000 4000

Wavenumber

Water

CarboxylCarboxyl

Soot

NitroSulfate

Glycol

Fuel

Phosphate

Anti-wear


Polymer Additive Identification by GC/FT-IR

• Reverse Engineering Customer wants to deformulate competitive product

Product is complex polymer with several additives

GC analysis alone was inconclusive

• Infrared spectroscopy was necessary for identification of additives


Nicolet® Nexus® GC/FT-IR System


Polymer Additives by GC/FT-IR

Real-Time Display

8 cm-1 Resolution

0.74 sec/spectrum


GC/FT-IR Peak Identification


TGA/FT-IR Rubber Gasket Characterization

•High pressure and temperature application

•Gasket from backup supplier fails

•TGA only reveals small difference

•TGA/IR reveals compositional differences


TGA/FT-IR System

• TGA

• FT-IR spectrometer

• TGA/IR interface

• OMNIC Series software


TGA/IR Data of Rubber Gaskets

• 8 cm-1 resolution

• DTGS detector

• 10.0 sec time resolution

• OMNIC Series software


TGA/IR Spectra of Rubber Gasket Samples


Library Search Results


Mobile and Portable Infrared Analysis

• Incident Preparedness and Response (IPAR)

•First Responders

•Fire Fighters

•Clandestine Lab Investigators

•WMD/CST

•US Army/US Navy


Implementation

• Mobile system offers full sampling flexibility in a small footprint

Expandability and flexibility

AC power necessary

GLP or 21 CFR Part 11 software tools

• Portable system offers rapid setup and simplicity of operation

Compact, integrated, transportable system

Flexible power sources - AC, 12 volt or battery

Laptop computer compatibility via USB


Mobile Solution

Dynamic Interferometer alignment

Rugged--Sealed and desiccated or Purgeable

Smart accessories ease sample preparation

Full OMNIC capability

IR Microscope ready

GLP, Validation

21 CFR Part 11 Compliance tools

Full laboratory capability in a small footprint


Hazardous Sample Analysis Accessory

• Smart Golden Gate Diamond ATR

• Natural Type IIa diamond

• Diamond brazed to tungsten

carbide disk

• Top plate removable for glove box

loading

• Sample anvil isolates sample from

environment

• Extremely easy-to-use and simple

decontamination


Hazardous Materials Analysis Mustard HD

-0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0.11

0.12

0.13

0.14

Ab

so

rba

nce

1000 1500 2000 2500 3000 3500

Wav enumbers (cm-1)


Conclusions - Sampling Techniques

• Thermo Electron FT-IR spectrometers provide a broad range of analytical solutions

• We develop new sampling technologies based upon your sampling needs

• Speed, resolution and sensitivity of our systems can be tuned to your experiment

• Let us know how we can help solve your analytical problems


Human Hair Analysis

• Verify the fiber to be consistent or inconsistent with hair fromthe suspect

• FT-IR microscope w/ ATR objective


Surface Analysis of Hair

• ATR, excellent surface analysis tool

• Maximizes surface response

Hair without Hairspray

Hairspray on Hair

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

Ab

sorb

an

ce 1000 2000 3000 4000

Wavenumbers (cm-1)


Surface Analysis of Hair

• Difference FT-IR bands consistent with PVA hair spray

• ATR microscopy - surface sensitive, non-destructive

Subtraction Result: Hairspray on hair - hair

PVA from Library

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Ab

sorb

an

ce 1000 2000 3000 4000

Wavenumbers (cm-1)


Fiber from Crime Scene

• Fiber Diameter - 20 microns

• ATR Objective Sample Area - 7 microns


Micro ATR Fiber Spectrum

20 micron diameter fiber by Micro-ATR

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

A

b

s

o

r

b

a

n

c

e

1000 1500 2000 2500 3000 3500 4000


Paint Chip Analysis

• Automotive Paint Identification

• Multilayered, 20-25 microns each

• Redundant Aperturing Required


View-Thru Aperturing - 15x15 microns

Analyze !Both Apertures

Lower ApertureNo Apertures


Paint Spectra

Grey Layer - 25 microns thick

Red Layer - 17 microns thick

Clear Layer - 25 microns thick

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.2

A

b

s

o

r

b

a

n

c

e

1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-1)


NIR Spectroscopy

Advantages

• Easier Remote sampling


• Glass is “transparent”

• Quick data collection

Disadvantages

• Difficult or impossible to interpret spectra

• More complex to develop methods

• Difficult to add extra compounds to a sample ID method


SabIR Near-IR Fiber Optic Accessory


NIR Fiber Optic Sampling

Aspirin Tablet in Packaging

0.5

1.0

Abso

rbance

6000 8000

Wavenumbers (cm-1)


Polyvinyl Chloride / Vinyl Acetate Copolymers

PVC100

PVC/AC 90/10

PVC/AC 87/13

PVC/AC 81/17

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Abs

orba

nce

5000 6000 7000 8000 9000 10000

Wavenumbers (cm-1)

Documents

Výběr z aplikací infračervené