1

1

Challenges and New Opportunities in Challenges and New Opportunities in Industrialising Raman Spectroscopy Industrialising Raman Spectroscopy

for PAT Applicationsfor PAT Applications

Pavel MatousekCentral Laser FacilityRutherford Appleton LaboratoryOxfordshireEngland

2

OutlineOutline

• Raman Method

• Current Status (challenges in PAT)

• Emerging Technologies (opportunities in PAT)- Spatially Offset Raman Spectroscopy SORS (deep layered

analysis)- Displaced Raman Spectroscopy (analysis of transparent

containers)- Transmission Raman (bulk analysis)

• Conclusions

2

3

Raman Technique - Overview

4

S1

ν=0

ν=1

Ramanlaser

S0

3

5

Raman spectrum of acetone with waterRaman spectrum of acetone with water

0

1000

2000

3000

4000

5000

6000

1000 1200 1400 1600 1800

wavenumbers

inte

nsity

Acetone1% water2% water3% water

0

1000

2000

3000

4000

5000

6000

1690 1710 1730

Aqueous samples, slurries, solids, liquids and gases Can analyse, for example:

6

Why Raman?

- High chemical specificity- Compatibility with water- ‘THz region’ included as a bonus- Uses UV/vis/NIR -> good spatial resolution

compared with MIR- Weak process – permits deep probing of materials- Can be portable- Can be relatively fast (if not image mapping)- Can be quantitative

- Bulk capability (TR)- Non-invasive deep layer capability (SORS)- Non-invasive probing of fluorescing containers (DR)- Medium cost (£10k’s)

Why Not Raman?

- Weak process – not a trace technique (~1%)- Can be swamped by fluorescence (NIR minimises the issue)

NEWNEW

NEWNEW

NEWNEW

IR

☺

☺☺☺

☺

☺☺

NIR

☺

☺☺☺☺

☺☺☺☺

☺

THz

☺

☺

☺☺☺☺

☺☺☺

☺

Raman

☺☺☺☺

☺☺☺☺

☺☺☺☺

ProPro’’s and Cons and Con’’s of Raman in PATs of Raman in PAT Renishaw’s data sheet: NExTl-cystene

‘Terahertz’region

1 THz = 33 cm-1

with turbid media

4

7

Ahura Truscan

Hand-held, battery operated

Examples of Raman Instruments for PAT Examples of Raman Instruments for PAT

Kaiser’s RamanRxn3™ PAT Analyzer

Kaiser’s PhAT System™ Raman Analyzerfor Solids Analysis

Renishaw inVia

• Remote data collection (fibres) • Robust operation in dusty environments• Compliance with powder explosive

environments• Non-expert operation• Real-time quantitative feedback • Fast data collection• Self calibration• Safety issues• Ambient light shielding• Sample fluorescence

Key Requirements/Issues

8

Deep Spectroscopy of Powders

Emerging Raman Techniques

5

9

RELEVANT PROBLEM NOT ADDRESSED BY RAMAN UNTIL RECENTLY:

Deep Non-invasive probing of turbid solids/slurries/liquids • In-depth• Through thick turbid plastic containers (bottles, capsules, pipes)

True bulk analysis or tablets/capsules

- often required in PAT applications

Seeing InvisibleSeeing Invisible

10

Issues in Deep Raman Issues in Deep Raman Spectroscopy in Turbid MediaSpectroscopy in Turbid Media

Conventional confocal Raman microscopy is applicable only to ‘shallow’ depths in turbid media (~ the photon transport length).

Key issues:Subsurface Raman signal is often overwhelmed by that from the surface layerMixed up signals – not clear which bottom and which top (unless composition is

known a priory)

top layer

lower layer

laser beam Raman

Raman collection aperture

6

11

laser Raman

Two Raman Approaches DevelopedTwo Raman Approaches Developed

a) Temporal b) Spatial

The variation of Δt or Δs leads to the variation of relative Raman intensities. Higher values lead to the diminishment of surface signal (Raman/fluorescence).

This change can be used by PCA to extract pure Raman spectra of layers.

Δt

surface

sub-surface

Prior Art - used in NIR, fluorescence, single-Raman-band tomography: • B.B.Das, Feng Lie, R.R. Alfano, Rep.Prog.Phys. 60(1997) 227.• J.Wu, Y.Wang, L.Perelman, I.Itzkan, R.R.Dasari, M. Feld, Appl. Opt. 34 (1995) 3425. • N.Everall, T.Hahn, P.Matousek, A.W.Parker, M.Towrie, Applied Spectroscopy 55 (2001) 1701.

Prior Art - used in NIR, fluorescence: • B.B.Das, Feng Lie, R.R. Alfano, Rep.Prog.Phys. 60 (1997) 227.• T.J.Pfefer, K.T.Schomacker, M.N.Ediger, N.S.Nishioka, Appl. Opt. 41 (2002) 4712.

ΔsRamanlaser

12

Spatially Offset Raman Spectroscopy (SORS)

laser

Raman

Δs

Δs … spatial offset

7

13

ResultsResults

0

5000

10000

15000

20000

25000

30000

35000

750 950 1150 1350 1550 1750

wavenumbers /cm-1

inte

nsity

/cou

nts

x

PMMA

0 mm

0.5 mm

1 mm

1.5 mm

2 mm

2.5 mm

t-stilbene

subsurface signal

conventional Raman

λ = 514 nmsurface

subsurface

P. Matousek, I. P. Clark, E. R. C. Draper, M. D. Morris, A. E. Goodship, N. Everall, M. Towrie, W. F. Finney and A. W. Parker, Appl. Spectrosc. 59 (2005) 393.

1 mm

PMMA (φ 20 μm)

trans-stilbeneΔs

14

SORS VariantsSORS Variants

0

2000

4000

6000

8000

10000

12000

0 1 2 3 4 5spatial offset (mm)

Ram

an in

tens

ity (c

ount

s)

top

bottom

0

2000

4000

6000

8000

10000

12000

0 1 2 3 4 5spatial offset (mm)

Ram

an in

tens

ity (a

.u.)

top

bottom

Point collection

Circular collection

……

….….

Inverse SORS …

z

α

Do

d

βro

rinner

ro

n

axicon

basic concept

high collectionefficiency

high collection efficiency & high sensitivity

J.H. McLeod, J. Opt. Soc. Am. 44, 592 (1954)B. Depret, P. Verkerk and D. Hennequin, Opt. Commun. 211, 31 (2002).

Axicon

Inverse SORSM.V. Schulmerich, K.A. Dooley, M.D. Morris, T.M. Vanasse, S.A. Goldstein, J. Biomed. Optics 11, 060502 (2006). P. Matousek, Applied Spectroscopy 60, 1341 (2006).

8

15

f# 1.4 spectrograph

(Kaiser)

827 nm diode laser (μLS)

SORS fibre (C Technologies)

NIR deep depletion liqN2 cooled CCD (PI)

SORS fibre input

Raman collection lens

Raman imaging lens

holographic notch filters(Kaiser) sample

SORS Instrumental SetupSORS Instrumental Setup

2 bandpassfilters (Semrock)

16

0

2000000

4000000

6000000

8000000

10000000

12000000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

SORS

conventional

Sudafed Dual Releifcapsulegreen10 s, 827 nm

x2

2800000

3300000

3800000

4300000

4800000

5300000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

SORS

conventional

Sudafed Dual Releifcapsulegreen10 s, 827 nm

x2

SORS Probing of Pharmaceutical Capsules

Raw spectra Backgrounds removed

capsule shell(highlyfluorescent)

active ingredient

laser beam RamanRaman collectionaperture

SORS

9

17

Counterfeit ApplicationsCounterfeit Applications

400 600 800 1000 1200 1400 1600 1800

100000

200000

300000 Conventional Raman

Wave numbers / cm-1

75000

150000

225000 Paracetamol

Inte

nsity

/ a.

u.

40000

50000

60000

70000 SORS corrected

Paracetamol in Bottle

C. Eliasson, P. Matousek, Analytical Chemistry 79 (2007) 1696.

Anti-malaria tablets: C. Ricci, C. Eliasson, N. A. Macleod, P. Newton, P. Matousek and S. G. Kazarian, Analytical and Bioanalytical Chemistry, in press 2007.

Wavenumbers /cm-1

SORSCounterfeit drugs issue: • R. Mukhopadhyay, Analytical Chemistry 79, 7, 2622 (2007)

1 s

18

Seeing Through PaintSeeing Through Paint

Raw Spectra Recovered Spectrum

0.00E+00

5.00E+06

1.00E+07

1.50E+07

2.00E+07

2.50E+07

3.00E+07

3.50E+07

1000 1100 1200 1300 1400 1500 1600

wavenumber (cm-1)

inte

nsity

(cou

nts)

a)

0 mm

3 mm

x 50

Inverse SORS

1000 1100 1200 1300 1400 1500 1600 1700

wavenumber (cm-1)

inte

nsity

(a.u

.)

b)

wood only

inverse SORS

Adhesion of paint/biofilms to substrates, rust detection, …

Painted wooden block

P. Matousek, Applied Spectroscopy 60 (2006) 1341.

10

19

Detection of Powders in EnvelopesDetection of Powders in Envelopes

Raw Spectra Recovered Spectrum

0

1000000

2000000

3000000

4000000

5000000

6000000

7000000

800 900 1000 1100 1200 1300 1400 1500 1600

wavenumber (cm-1)

inte

nsity

(cou

nts)

a)

0 mm

3 mm

x 40

Inverse SORS

800 900 1000 1100 1200 1300 1400 1500 1600

wavenumber (cm-1)

inte

nsity

(a.u

.)

b)

sugar only

inverse SORS

Security screening

20

Slurries in PAT ApplicationsSlurries in PAT Applications

200 400 600 800 1000 1200 1400 1600 1800

40000

60000

80000

Wavenumbers / cm-1

45000

60000

75000

Inte

nsity

400000

500000

paracetamol slurry

paracetamol solution

crystalline paracetamol

Preliminary data

11

21

Detection of Powders in Plastic Translucent ContainersDetection of Powders in Plastic Translucent Containers

400 600 800 1000 1200 1400 1600

Wavenumbers / cm-1

bottle only

Inte

nsity

/ a.

u.

CR through bottle

SORS through bottle

sugar

SORS through bottle

e.g. illicit drugs or powder explosives

1 s

22

800 1000 1200 1400 1600 1800

wavenumbers (cm-1)

Δs = 3 mmΔs = 0 mm

human bone through 2 mm of skin (thumb) in vivo (200 s) at safe levels

2 mW

Human Bone Through Skin Human Bone Through Skin In VivoIn Vivo

P. Matousek, E.R.C. Draper, A.E. Goodship, I.P. Clark, K. Ronayne, A.W.Parker, Applied Spectroscopy 60 (2006) 758.

Similar research is also performed by a group of Professor Michael Morris (University of Michigan): M.V. Schulmerich, K.A. Dooley, T.M. Vanasse, S.A. Goldstein and M.D. Morris, Appl. Spectrosc. 61, (2007) 671.

λ = 827 nm

SORS circular collection

12

23

Displaced Raman Approach (DR)

A hybrid between SORS and conventional Raman‘One geometry for all uses’

24

laser

Raman

Δdlaser

Raman

Spatially Offset Raman Spectroscopy (SORS)

Δs

Δs … spatial offset

For diffusely scattering samples For transparent samplesREDUCES fouling problem or window fluorescence

Displaced Raman Spectroscopy

Displaced Raman Concept

13

25

Raman collectionsystem

spectrometer

CCD

laser

fibre bundle

Displaced Raman Deployment

26

Detection of Liquids Through BottlesDetection of Liquids Through Bottles

Displaced Raman

800 1000 1200 1400 1600

Wavenumbers / cm-1

jar only

Inte

nsity

/ a.

u.

concealed H2O

2

SORS through jar

CR through jar

content

e.g. liquid explosives

Not applicable to metals

C. Eliasson, N.A. Macleod, P. Matousek, Non-invasive Detection of Concealed Liquid Explosives using Raman Spectroscopy, Anal. Chem., in press, 2007.

1 s

14

27

NonNon--invasive Detection of Cocaine Dissolved in Ruminvasive Detection of Cocaine Dissolved in Rumethanol

cocaine

300 g

Displaced Raman

in collaboration with UK’s Government Department

1 s

= cocaine

28

Bulk Probing of Solids(Transmission Raman)

Elimination of the sub-sampling problem

15

29

Transmission RamanTransmission Raman

First use of transmission geometryB. Schrader, G. Bergmann, Fresenius. Z. Anal. Chem. 225, 230 (1967)

Sub-sampling problem of conventional backscattering geometry discussedH. Wang, C.K. Mann, T.J. Vickers, Appl. Spectrosc. 56, 1538 (2002).J. Johansson, S. Pettersson, S. Folestad, J. Pharnaceutical and Biomedical Analysis 39, 516 (2005).

Key benefit: Elimination of the sub-sampling problemP. Matousek, A.W. Parker, Applied Spectroscopy 60 (2006) 1353.

1

10

100

1000

10000

100000

1000000

0 1 2 3 4d1 (mm)

Ram

an in

tens

ity (c

nts)

transmitted

backscatteredR L

L

R

Impurity depth (mm)

Monte Carlo

laser

Raman

Transmission Raman

Prior Art:

30

capsule

Raman

spectrometer(Kaiser 1.8i) CCD

Andor (NIR)

laser

fibre bundle

Transmission Raman Spectroscopy

Bulk analysisEliminates sub-sampling problemSuppression of capsule Raman

and fluorescence interference

830 nm100 mWφ 2 mm

16

31

Bulk Tablet CharacterisationBulk Tablet Characterisation

P. Matousek, A.W. Parker, Applied Spectroscopy 60 (2006) 1353.

900 1100 1300 1500 1700

wavenumber (cm-1)

inte

nsity

(cnt

s/s)

b

a)

p only

t only

x 1

x 0.02

x 0.02

x 1 R L

P

T

R L

P

T

LR

P T

LR

P T

900 1100 1300 1500 1700

wavenumber (cm-1)

inte

nsity

(cnt

s/s)

b)

p only

t only

x 1

x 0.02

x 25

x 25L

R

P

TL

R

P

T

L

R

P T

L

R

P T

Conventional backscattering Transmission

The impurity layer is visible at any locationOnly surface layer is visible

R L

L

R

tablet impurity

tablet

impurity

Elimination of sub-sampling problem!

32

Raw spectra!0

2000000

4000000

6000000

8000000

10000000

12000000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

5000

10000

15000

20000

transmission

conventional

Sudafed Dual Releifcapsulegreen10 s, 827 nm

0

500000

1000000

1500000

2000000

2500000

3000000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

10000

20000

30000

40000

50000

conventional

Lemsip Max capsuleyellow10 s, 827 nm

transmission

0

1000000

2000000

3000000

4000000

5000000

6000000

7000000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

5000

10000

15000

20000

25000

30000

35000

40000

conventional

Lemsip Max capsulered10 s, 827 nm

transmission0

100000

200000

300000

400000

500000

600000

700000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

10000

20000

30000

40000

50000

60000

70000

80000

conventional

paracetamol capsulewhite10 s, 827 nm

transmission

05000

100001500020000250003000035000400004500050000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

10000

20000

30000

40000

50000

60000

70000

conventional

paracetamol capsuleblue0.1 / 10 s, 827 nm

0.1 s

10 s *

transmission0

1000000

2000000

3000000

4000000

5000000

6000000

7000000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

10000

20000

30000

40000

50000

60000

70000

80000

90000

conventional

Ibuprofen capsuleblue10 s, 827 nm

transmission

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

10000

20000

30000

40000

50000

60000

conventional

Beechams capsulered10 s, 827 nm

transmission0

1000000

2000000

3000000

4000000

5000000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0

5000

10000

15000

20000

25000

30000

conventional

Sudafed CongestionRelief capsuleyellow10 s, 827 nm

transmission

 

 

λ = 827 nm80 mW

10 s

NonNon--invasive Probing of Coloured Capsulesinvasive Probing of Coloured Capsules

P. Matousek, A.W. Parker, Journal of Raman Spectroscopy 38 (2007) 563.

Transmission Raman

Capsule Fluorescence Signal Suppressed

17

33

Quantification of Capsule Content using Transmission RamanQuantification of Capsule Content using Transmission Raman

200 400 600 800 1000 1200 1400 1600 1800

Inte

nsity

/ a.

u.

Wavenumbers/ cm-1

capsule shell

Conventional RamanRenishaw microscope system

Transmission RamanLaboratory system

capsule content

API

caps

ule

shel

l

Capsule Raman Signal Suppressed

(x33)

In collaboration with Pfizer(L. Jayes, F. Clarke, S. Hammond, M.R. Smith)

5 s

34

Quantification of Capsule Content using Transmission RamanQuantification of Capsule Content using Transmission Raman

PLS analysis

5 s

API

±0.5 %

API

API

API

±0.5 %

API

API

Transmission Raman

In collaboration with Pfizer(L. Jayes, F. Clarke, S. Hammond, M.R. Smith)

18

35

Calcified MaterialCalcified Material((chicken breast tissue chicken breast tissue -- 16 mm thick)16 mm thick)

backgrounds subtracted

020000400006000080000

100000120000140000160000180000200000

700 900 1100 1300 1500 1700

Wavenumber (cm-1)

Inte

nsity

(cnt

s)

0200400600800100012001400160018002000

Inte

nsity

(cnt

s)

hap

com

hap in tissue

com in tissue

b)

P. Matousek, N. Stone, Journal of Biomedical Optics 12 (2007) 024007.

hap … calcium hydroxyapatitecom …calcium oxalate monohydrate

λ = 827 nm60 mW

100 s

Transmission Raman

36

Passive Boosting of Raman Signals for Higher Sensitivity &

Shorter Acquisition Times

19

37

In most applications involving deep layer probing weak Raman signals are present with noise limiting the sensitivity and penetration depth.

For maximum sensitivity and penetration depth it is desirable toimprove S/N which can be accomplished by enhancing Raman signals.

Adjustable parameterseg acquisition timelaser powercollection efficiency (Kathryn Dooley, Talk #381, Wednesday)by other means ?????

Penetration Depth and Sensitivity are Typically Noise Limited.

Issues in Deep SpectroscopyIssues in Deep Spectroscopy

38

Problem of Coupling Laser Radiation into Turbid MediumProblem of Coupling Laser Radiation into Turbid Medium

kdkkdrakII oP coshsinh)( ++

=kdkkdra

kdrIJ oP coshsinh)(sinh

++=

11+

≈rd

II oP

rd

IJ oP 11

1

+≈

P. Kubelka, F. Munk, Z. Tech. Phys. 12, 593-601 (1931).B. Schrader, G. Bergmann, Fresenius. Z. Anal. Chem. 225 (1967) 230.

Loss of radiation at the coupling interface

r … scattering coefficient

Io

IpJP

0

0.2

0.4

0.6

0.8

1

0 20 40 60 80 100r.d

fract

ion

of in

cide

nt in

tens

ity re-radiated backwards

transmitted

J p

I p

Reflective enclosure solution:B. Schrader, G. Bergmann, Fresenius. Z. Anal. Chem. 225 (1967) 230.J.C. Henderson, Q. Su, R. Grobe, Laser Physics 14 (2004) 515.

d

20

39

turbid medium

collimatedlaser beam

dielectricbandpass filter(‘unidirectional’ mirror)

laserphoton

emerging Raman photons

detector

Solution Solution –– ‘‘UnidirectionalUnidirectional’’ MirrorMirror

0.80.820.840.860.88

0.90.920.940.960.98

1

0 20 40 60 80 100Angle of incidence (deg)

Rel

ativ

e w

avel

engt

h ch

ange

S

664

684

704

724

744

764

784

804

824

Wav

elen

gth

(nm

)

trans

mis

sion

normal incidence

wavelength (nm)

Θ > 0o Θ ~ 0o

λlaserRaman

2)/(sin1 effo nΘ−= λλ

40

S/N Improvement with Medium Performance Raman SystemsS/N Improvement with Medium Performance Raman Systems

Signal enhancing bandpass filter

laser

RamanParacetamol tablet

Transmission RamanParacetamol tablet (3.9 mm thick)

S/N improvement ~ enhancement factor ~ 10 ! (equivalent to 100-times longer acquisition time)

S/N detector thermal noise limited

250 mW830 nm1 sOcean Optics QE65000t = -15 oC

1000 1200 1400 1600 1800

Wavenumber (cm-1)

Inte

nsity

x10 bare

with bandpass filter

1s

P. Matousek, Applied Spectroscopy 61 (2007) 845.

02468

1012

0 1 2 3 4 5Separation from sample (mm)

Enh

ance

men

t fac

tor

Signal dependence on filter-sample separation

02468

1012

0 1 2 3 4 5Separation from sample (mm)

Enh

ance

men

t fac

tor

Signal dependence on filter-sample separation

21

41

ConclusionsConclusions

RamanComing out of age: A robust, simple method.Compatible with PAT goals (enables process monitoring and understanding)Software/instrumentation development – eliminates need for specialistAdapted for production environment (e.g. Kaiser)Cost reduced over the last decade from several $100,000’s to $10,000’s

New Emerging Technology Removes Key Limitations of RamanSORS Non-invasive probing through plastic diffusely scattering

(translucent) containers – pipes/bottles – SORSDR Combines the benefits of SORS with conventional Raman for probing

transparent bottles enabling surface fluorescence rejection TR Bulk quantitative analysis (removes the subsampling problem) –

(potential to displace NIR in some applications)

P. Matousek, Chem. Soc. Rev. 36 (2007) 1292.

http://www.clf.rl.ac.uk/Facilities/LSF/SORS/home.htm

Further reading:

42

AcknowledgementsAcknowledgements

Supported by CLIK Knowledge Transfer (Dr D. Andrews), STFC, NESTA, Rainbow Seed Fund, LiteThru Ltd, EPSRC (EP/D037662/1).

C. Eliasson, N. Macleod, A.W. Parker, I.P. Clark, K. Ronayne, M. Towrie Rutherford Appleton Laboratory, UKM.D. Morris, W.F. FinneyChemistry, University of Michigan, USAN. EverallIntertek, UKA.E. Goodship, E.R.C. Draper Royal Veterinary College, Hertfordshire, UKN. StoneBiophotonics Research Group, Gloucestershire Royal Hospital, UKS. Kazarian, C. RicciImperial College, London, UKL. Jayes, F. Clarke, S. Hammond, M.R. SmithPfizer (UK/USA) M. Claybourn, C. Roger, J. Johansson, O. SvenssonAstraZeneca (UK/Sweden)