prof. robert p. lucht school of mechanical engineering, purdue university, w. lafayette, in

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Purdue University

School of Mechanical Engineering

Selective, Sensitive Detection of Dipicolinic Acid and Other

Molecules (NO, C6H6, C2H2) Using CARS Techniques

Selective, Sensitive Detection of Dipicolinic Acid and Other

Molecules (NO, C6H6, C2H2) Using CARS Techniques

Prof. Robert P. Lucht

School of Mechanical Engineering, Purdue University, W. Lafayette, IN

Institute for Quantum Studies, Texas A&M University, College Station, TX

2003 TAMU/DARPA/ONR Workshop on Quantum Optics, Jackson Hole, WY, July 7-11, 2003


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AcknowledgmentsAcknowledgments

• Funding Support from DARPA, DOE Office of Basic Energy Sciences, ARO

• Experiments: Sherif Hanna, Waruna Kulatilaka, Jonathan DuBois (Texas A&M MEEN graduate students), Dr. Zane Arp (now at Los Alamos)

• Modeling: Joel Kuehner (Univ. Illinois)

• Prof. Marlan Scully (Physics), Dr. Tomas Opatrny (Physics), Prof. Phil Hemmer (EE)


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Outline of the Presentation Outline of the Presentation

• Introduction and Motivation

• Laser Diagnostics in Combustion: Dual-Pump CARS

• Electronic-Resonance-Enhanced CARS of NO: Experiments and Modeling

• Electronic Resonance CARS of C2H2

• CARS Detection of Solid DPA

• Conclusions and Future Work


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Triple-pump CARS measurements

performed in laminar hydrogen/air

diffusion flame.

Simultaneous acquisition of

single-shot H2/N2 and H2/O2

spectra demonstrated.

CARS Experiments in Flames CARS Experiments in Flames


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Dual-Pump CO2/N2 CARS Performed in Exhaust of JP8-Fueled Combustor at WPAFB

Dual-Pump CO2/N2 CARS Performed in Exhaust of JP8-Fueled Combustor at WPAFB


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Dual-Pump CARS of N2/CO2Dual-Pump CARS of N2/CO2


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Dual-Pump CARS Spectrum of N2/CO2 from Hencken Burner

Dual-Pump CARS Spectrum of N2/CO2 from Hencken Burner

-20

0

20

40

60

80

100

2250 2300 2350 2400

ExptTheoryExpt - Theory

(CARS Intensity)

1/2 (arb. units)

Raman Shift ( cm -1 )

CO2 Mole Fraction:

From Flowrates = 0.123From CARS = 0.139Temperature = 936 K

N2

CO2

CO2


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Anthrax Spore Detection Anthrax Spore Detection

• Weaponized anthrax mailed to Senate offices, National Enquirer offices Fall 2001

• Anthrax difficult to detect in short period of time

• Anthrax spores can remain dangerous for years

• Anthrax diagnosis must be rapid to prevent severe damage or death


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Ultraviolet Resonant Raman SpectraUltraviolet Resonant Raman Spectra

3b: Calcium Dipicolinate2b: Bacillus Cereus1b: Bacillus Megaterium


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Research Roadmap Research Roadmap

“Ordinary” CARS ERE CARS

Benzene CARSLiquid, 992 cm-1

DPA CARS Powder

Polycrystalline 998 cm-1

NO CARSGas Phase

C2H2 CARSGas Phase

DPA, Benzene CARS

DPA in Spores


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Electronic-Resonance-Enhanced Coherent Anti-Stokes Raman

Scattering (ERE CARS)

Electronic-Resonance-Enhanced Coherent Anti-Stokes Raman

Scattering (ERE CARS)

• ERE CARS was explored as a combustion diagnostic technique by Taran, Attal-Tretout and co-workers from the late 1970s to early 1990s

• Technique was complicated both experimentally and theoretically because only two laser frequencies were used, both electronically resonant

• Our ERE CARS approach is a variant on the dual-pump CARS technique, demonstrated on NO in gas cell to gain understanding of the physics


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Druet and TaranProg Quant Elec1979

ER CARS, Pump 1 = Pump 2ER CARS, Pump 1 = Pump 2


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Electronic Resonance CARS of NO Electronic Resonance CARS of NO

Ground Electronic Level

v" = 0v" = 1v" = 2

v' = 0v' = 1v' = 2

Excited Electronic Level

ΔχCARS ∼ (Δ − i Γ)−1


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Electronic Resonance CARS Detection of NO


λ/2

Pol

λ/2PolPol Beam Dumps

EnergyMeter

Solar-BlindPMT

0.5-MeterSpectrometer

λ/2

591 nm

532 nm

Aperture

Filters70% T 226 nm1%T 236 nm

ER CARS226 nm

Q-switched Nd:YAG LaserInjection-Seeded

Q-switchedNd:YAG Laser

DelayGenerator

GatedIntegrator

Computer NarrowbandDye Laser

472 nm 355 nm

Gas CellNO in N2 Buffer Gas

BBO 2ω Crystal

236 nm

NarrowbandDye Laser

591 nm


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ERCARS Beam Geometry ERCARS Beam Geometry


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Stokes Scan, Fixed Pump 2Stokes Scan, Fixed Pump 2


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NO CARS Spectrum: Theory NO CARS Spectrum: Theory

0 100

2 100

4 100

6 100

8 100

1 101

590.7 590.8 590.9 591 591.1 591.2 591.3 591.4 591.5

Theoretical CARS Spectrum: 1% NO in N2

CARS Signal (arb. units)

Stokes Dye Laser Wavelength (nm)

Pressure = 190 TorrNo resonance enhancement


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CARS Detection of NO CARS Detection of NO


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Polarization Suppression of Nonresonant Background

Polarization Suppression of Nonresonant Background

532 nm

591 nm

236 nmNonresonantBackground

NO ResonantCARS Signal

Transmission Axis forPolarizer in CARSSignal Channnel


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NO Electronic Resonance CARS with Background Suppression



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Stokes Scan, Comparison of Theory and Experiment

Stokes Scan, Comparison of Theory and Experiment


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Pump 2 Scan, Fixed StokesPump 2 Scan, Fixed Stokes


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UV Pump Scan, Comparison of Theory and Experiment

UV Pump Scan, Comparison of Theory and Experiment


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Energy Level Diagram Energy Level Diagram


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CARS SusceptibilityNear Electronic Resonance

CARS SusceptibilityNear Electronic Resonance

()()()412312434(0)1221211:,,abbabaaddbddadabccabccaaaccbcaNiiχωωωωωωωγμμωωγμμμμρωωωω−=−+−⏐ ↔√√−−↵⏐ ↔+√+−↵hResonanceenhancement

“Normal” Ramancross section

Raman resonance


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Detailed Energy Level DiagramDetailed Energy Level Diagram


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Acetylene ERE CARS Spectrum Acetylene ERE CARS Spectrum

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

1955 1960 1965 1970 1975 1980 1985

5000 ppm C2H

2

P = 66.7 kPa

λ3 = 239.0 nm

λ3 = 240.5 nm

λ3 = 242.0 nm


Raman Shift (cm-1)


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Theoretical Acetylene CARS Spectrum


0.00

200.00

400.00

600.00

800.00

1000.00

1200.00

1955 1960 1965 1970 1975 1980 1985

80% C2H

2

P = 60 kPa


Raman Shift (cm-1)


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Acetylene Electronic Spectrum Acetylene Electronic Spectrum

Watson et al., J. Mol.

Spectrosc. 95, 101 (1982)


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DPA, Benzene CARS SystemDPA, Benzene CARS System


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DPA, Benzene CARS SpectraDPA, Benzene CARS Spectra

0

0.04

0.08

0.12

0.16

960 968 976 984 992 1000 1008

DPA CARSPolycrystalline

Benzene CARSLiquid


Raman Shift (cm-1)


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ConclusionsConclusions

• NO detected by electronic resonance CARS, spectrum observed clearly for 100 ppm NO

• Sensitive, selective detection of minority species demonstrated, good agreement between model and experiment

• ERE CARS of C2H2 demonstrated, significant resonant enhancement observed

• Very strong CARS signal from DPA demonstrated, narrow spectral feature at 998 cm-1 observed


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Research Roadmap Research Roadmap

“Ordinary” CARS ERE CARS

Benzene CARSLiquid, 992 cm-1

DPA CARS Powder

Polycrystalline 998 cm-1

NO CARSGas Phase

C2H2 CARSGas Phase

DPA, Benzene CARS

DPA in Spores


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Future WorkFuture Work

• Experimental measurements of dissolved DPA and/or solid DPA particles and benzene by ERE CARS

• Study two different ERE CARS schemes for DPA: (1, 2 visible, 3 ultraviolet) or (1, 2 ultraviolet, 3 = 1)

• Work towards ERE CARS microscopy, focus UV beam(s) to less than 10 microns


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ERE CARS of DPA ERE CARS of DPA


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Multi-Pump CARS Measurements in Combustion Systems

Multi-Pump CARS Measurements in Combustion Systems

• Electronic resonance CARS technique demonstrated in this work is a variant of the technique of dual-pump CARS

• Dual-pump CARS developed for simultaneous measurement of two species in flames


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Electronic Resonance Enhancement Factor

Electronic Resonance Enhancement Factor

λ0 = 532 nm

()()()()43434440434300,accbaccbcccacacacaaccbaccbccaccacaiiiμμμμωωγωωγβωωμμμμωωωωγ⏐ ⏐ √√√√−−−−↵↵=≅⏐ ⏐ √√√−−−↵↵


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Electronic Resonance Enhancement Factor – Saturated 3

Electronic Resonance Enhancement Factor – Saturated 3


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0.00

5.00

10.00

15.00

1955 1960 1965 1970 1975 1980 1985

5000 ppm C2H

2

P = 60 kPa


Raman Shift (cm-1)


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Single-Shot Dual-Pump CO2/N2 CARS Spectrum from JP8-

Fueled Combustor

Single-Shot Dual-Pump CO2/N2 CARS Spectrum from JP8-

Fueled Combustor

0

5

10

15

20

25

30

35

40

1320 1330 1340 1350 1360 1370 1380 1390 1400

ExptTheory

(CARS Intensity)

1/2

Raman Shift (cm-1)

T = 1133 Kx

CO2 = 0.062


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Third-order Perturbation TheoryResult for CARS Susceptibility

Third-order Perturbation TheoryResult for CARS Susceptibility

()()()()()()()412312433444(0)122121211221:,,abbabaaddbaddbddadadbdabccabccaaaccacacacabccabccacbcbcbNiiiiiiχωωωωωωωγμμμμωωγωωγμμμμρωωγωωγμμμμωωγω−=−+−⏐ ↔+√√−−++↵⏐ ↔+√√+−−−↵−+−++h()(0)1bbcaiρωγ⏐ √√+↵


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Third-order CARS SusceptibilityNear Electronic Resonance

Third-order CARS SusceptibilityNear Electronic Resonance

~0

~0

()()()()()()()412312433444(0)122121211221:,,abbabaaddbaddbddadadbdabccabccaaaccacacacabccabccacbcbcbNiiiiiiχωωωωωωωγμμμμωωγωωγμμμμρωωγωωγμμμμωωγω−=−+−⏐ ↔+√√−−++↵⏐ ↔+√√+−−−↵−+−++h()(0)1bbcaiρωγ⏐ √√+↵


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ER CARS, Pump 1 = Pump 2ER CARS, Pump 1 = Pump 2

Doerk et al.Appl Phys B1997


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Pump 2 Scan, Comparison of Theory and Experiment

Pump 2 Scan, Comparison of Theory and Experiment


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NO Electronic SpectroscopyNO Electronic Spectroscopy

J = N + S


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NO Electronic SpectroscopyNO Electronic Spectroscopy

J = N - S

prof. robert p. lucht school of mechanical engineering, purdue university, w. lafayette, in

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