ning chai and robert p. lucht purdue university, west lafayette, indiana 47907 sukesh roy

APPLIED LASER SPECTROSCOPY LABORATORYSCHOOL OF MECHANICAL ENGINEERING

Electronic-Resonance-Enhanced Coherent Anti-Stokes Raman Scattering of Nitric

Oxide: Non-Perturbative Time-Dependent Modeling

Electronic-Resonance-Enhanced Coherent Anti-Stokes Raman Scattering of Nitric

Oxide: Non-Perturbative Time-Dependent Modeling

Ning Chai and Robert P. Lucht Purdue University, West Lafayette, Indiana 47907

Sukesh RoySpectral Energies, LLC, 2513 Pierce Avenue, Ames, IA 50010

James R. GordAir Force Research Laboratory, Propulsion Directorate, Wright-

Patterson AFB, Ohio 45433

AIAA Aerospace Sciences Meeting Orlando, FL January 7, 2010


AcknowledgmentsAcknowledgments

Funding for this research was provided by the Air Force Office of Scientific Research under Contract No. FA9550-05-C-0096 (Dr. Julian Tishkoff, Program Manager) and by

the Air Force Research Laboratory,Propulsion Directorate, Wright-Patterson Air Force Base,

under Contract No. F33615-03-D-2329, and by the U.S. Department of Energy, Division of Chemical Sciences,

Geosciences and Biosciences, under Grant No. DE-FG02-03ER15391.


Outline of the Presentation Outline of the Presentation

• Introduction and Motivation

• Scanning Stokes ERE CARS

• Density Matrix Modeling: Saturation and Stark Shifting Effects

• Broadband Stokes Vibrational ERE CARS

• Density Matrix Modeling of Broadband Stokes Vibrational ERE CARS

• Conclusions and Future Work


Introduction and MotivationIntroduction and Motivation

• Oxides of nitrogen (NOx) are important atmospheric pollutants their major source being emissions is from combustion during transportation and power generation. Most NOx is produced in the form of nitric oxide (NO).

• ERE CARS is a very promising method for detecting NO in high-pressure combustion systems, overcomes numerous issues associated with LIF detection (quenching, laser beam absorption, interfering species, soot interferences).


Vibrational Electronic Resonance

CARS of NO

Vibrational Electronic Resonance

CARS of NO

53

2n

m

59

1n

m

23

6n

m

22

6n

ma

b

c

d

A2+

X2

Va= 0, Ja

Vb= 1, Jb=Ja

Vc= 0, Jc=Jb, Jb+1, Jb-1


ERE CARS Phase MatchingERE CARS Phase Matching


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


Scanning ERE CARS Experimental System Scanning ERE CARS Experimental System


UV Probe Scan, Fixed Stokes Beam Frequency

UV Probe Scan, Fixed Stokes Beam Frequency


Numerical Model of CARS in Nitric Oxide: Raman Q1(8.5), Probe P1(8.5)

Numerical Model of CARS in Nitric Oxide: Raman Q1(8.5), Probe P1(8.5)


Time-Dependent Density Matrix Equations for the Laser Interaction


Rate of change of population of state j:

Time development of coherence between states i and j:

Coupling of laser radiation and dipole moment for states j and m:

1 2 3, , , ,jm jm jmV E r t E r t E r t E r t

( )jjjm mj jm mj j jj mj mm

m m

iV V

t

( ) ( )ijij ij ij im mj im mj

m

ii V V

t


1 4exp expkg kg kgt t i t t i t

2 3exp expke ke ket t i t t i t

1 2expeg egt t i t



The off-diagonal density matrix elements are written in terms of slowly varying amplitude functions and a term that oscillates at the frequency or frequencies of interest for each term:

The envelope functions and polarizations for the pump, Stokes, and probe beams are specified.


Vibrational ERE CARS in Nitric Oxide: Raman Q1(4.5), Probe R1(4.5)

Raman Q1(10.5), Probe R1(10.5)

Vibrational ERE CARS in Nitric Oxide: Raman Q1(4.5), Probe R1(4.5)

Raman Q1(10.5), Probe R1(10.5)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

44212 44214 44216 44218 44220 44222

ExperimentTheory

Nor

mal

ized

ER

E C

AR

S S

igna

l

ERE CARS Signal Frequency (cm-1)

Raman Q1(4.5)

Probe R1(4.5)

Raman Q1(10.5)

Probe Q1(10.5)


Scanning Probe Vibrational ERE CARS in Nitric Oxide: Low Laser Powers


0

2

4

6

8

10

42280 42300 42320 42340 42360 42380 42400

Density Matrix CalculationExperiment

CA

RS

Sig

nal

Probe Frequency (cm-1)

Q1

QP21

(2.5) R1

RQ21

(2.5)

P1

(2.5)

0

2

4

6

8

10

12

14

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(4.5) R1

RQ21

(4.5)

P1

(4.5)

(a) (b)

(c) (d)

0

2

4

6

8

10

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(3.5)R

1

RQ21

(3.5)

P1

(3.5)

0

2

4

6

8

10

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(7.5)

R1

RQ21

(7.5)P

1

(7.5)



Scanning Probe Vibrational ERE CARS in Nitric Oxide: Low Laser Powers0

2

4

6

8

10

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(2.5) R1

RQ21

(2.5)

P1

(2.5)

0

2

4

6

8

10

12

14

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(4.5) R1

RQ21

(4.5)

P1

(4.5)

(a) (b)

(c) (d)

0

2

4

6

8

10

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(3.5)R

1

RQ21

(3.5)

P1

(3.5)

0

2

4

6

8

10

42280 42300 42320 42340 42360 42380 42400


CA

RS

Sig

nal


Q1

QP21

(7.5)

R1

RQ21

(7.5)P

1

(7.5)


Scanning Probe

Vibrational ERE CARS: Low Laser

Powers

Scanning Probe

Vibrational ERE CARS: Low Laser

Powers 0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal

Probe Freqeuncy (cm-1)

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


(a) (b)

(c) (d)

I (W/m2)

P:1.5x1014

St:1.5x1014

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:2.0x1012

I (W/m2)

P:1.5x1015

St:1.5x1015

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:5.0x1013

Q1(7.5)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(8.5)

Q1(6.5)

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


I (W/m2)

P:5x1014

St:5x1014

Pr:1012

(a) I (W/m2)

P:1x1015

St:1x1015

Pr:1012

I (W/m2)

P:1016

St:1016

Pr:1012

I (W/m2)

P:1x1015

St:1x1015

Pr:3x1013

(b)

(c) (d)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(7.5)

Q1(8.5)

Q1(6.5)

Expt

Theory


Scanning Probe

Vibrational ERE CARS: Low Probe

Power, Moderate Pump and

Stokes Powers

Scanning Probe



Stokes Powers

Expt

Theory

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


I (W/m2)

P:5x1014

St:5x1014

Pr:1012

(a) I (W/m2)

P:1x1015

St:1x1015

Pr:1012

I (W/m2)

P:1016

St:1016

Pr:1012

I (W/m2)

P:1x1015

St:1x1015

Pr:3x1013

(b)

(c) (d)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(7.5)

Q1(8.5)

Q1(6.5)

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


(a) (b)

(c) (d)

I (W/m2)

P:1.5x1014

St:1.5x1014

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:2.0x1012

I (W/m2)

P:1.5x1015

St:1.5x1015

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:5.0x1013

Q1(7.5)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(8.5)

Q1(6.5)


Scanning Probe


Power, High Pump and

Stokes Powers

Scanning Probe


Power, High Pump and

Stokes Powers

Expt

Theory

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


I (W/m2)

P:5x1014

St:5x1014

Pr:1012

(a) I (W/m2)

P:1x1015

St:1x1015

Pr:1012

I (W/m2)

P:1016

St:1016

Pr:1012

I (W/m2)

P:1x1015

St:1x1015

Pr:3x1013

(b)

(c) (d)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(7.5)

Q1(8.5)

Q1(6.5)

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


(a) (b)

(c) (d)

I (W/m2)

P:1.5x1014

St:1.5x1014

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:2.0x1012

I (W/m2)

P:1.5x1015

St:1.5x1015

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:5.0x1013

Q1(7.5)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(8.5)

Q1(6.5)


Scanning Probe

Vibrational ERE CARS: High Probe


Stokes Powers

Scanning Probe

Vibrational ERE CARS: High Probe


Stokes Powers

Expt

Theory

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


I (W/m2)

P:5x1014

St:5x1014

Pr:1012

(a) I (W/m2)

P:1x1015

St:1x1015

Pr:1012

I (W/m2)

P:1016

St:1016

Pr:1012

I (W/m2)

P:1x1015

St:1x1015

Pr:3x1013

(b)

(c) (d)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(7.5)

Q1(8.5)

Q1(6.5)

0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


0.0

0.2

0.4

0.6

0.8

1.0

42310 42320 42330 42340 42350 42360 42370 42380

CA

RS

Sig

nal


(a) (b)

(c) (d)

I (W/m2)

P:1.5x1014

St:1.5x1014

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:2.0x1012

I (W/m2)

P:1.5x1015

St:1.5x1015

Pr:2.0x1012

I (W/m2)

P:3.0x1014

St:3.0x1014

Pr:5.0x1013

Q1(7.5)

R1(7.5)

R1(8.5)

R1(6.5)

Q1(8.5)

Q1(6.5)


Scanning Probe

Vibrational ERE CARS: Stark Shift

Effects

Scanning Probe

Vibrational ERE CARS: Stark Shift

Effects


Broadband Stokes Vibrational ERE CARS

Broadband Stokes Vibrational ERE CARS

0.003 cm-1

50 cm-1

0.1 cm-1


Broadband Stokes ERE CARS System Broadband Stokes ERE CARS System


Broadband Stokes ERE CARS System: Spectrally Narrowed BBDL

Broadband Stokes ERE CARS System: Spectrally Narrowed BBDL


Broadband Stokes ERE CARS Signal in Jet of N2 with 1000 ppm NO at 300 K

Broadband Stokes ERE CARS Signal in Jet of N2 with 1000 ppm NO at 300 K


Single-Shot NO ERE CARS in Counterflow H2/Air Flame: Q1(19.5) Line

Single-Shot NO ERE CARS in Counterflow H2/Air Flame: Q1(19.5) Line

• Estimated single-shot detection limit of 10 ppm based on an OPPDIF prediction of 30 ppm NO, 3.7 mm above the fuel nozzle


DNI Modeling of Broadband Stokes Vibrational ERE CARS


• Same set of time-dependent density matrix equations as for scanning ERE CARS.

• Multi-mode laser models used for Stokes (50 cm-1 FWHM) and for probe (0.1-0.2 cm-1 FWHM). Random phase, Gaussian random amplitude for the modes.

• Time-dependent ERE CARS signal calculated. The signal is then Fourier transformed to generate the ERE CARS spectrum.




0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

1400.0

44200 44205 44210 44215 44220 44225 44230 44235 44240

Raman Q1(4.5) and Q

1(10.5)

Probe R1(4.5)

Cou

nts


0.0

5.0 10-5

1.0 10-4

1.5 10-4

2.0 10-4

-15 -10 -5 0 5 10 15E

RE

CA

RS

Sig

nal

(ar

b.

units

)

Signal Frequency (cm -1)

Q1(10)/Q

1(10)

Q1(4)/R

1(4)

Experiment Theory


Saturation Effects in Broadband Stokes Vibrational ERE CARS

Saturation Effects in Broadband Stokes Vibrational ERE CARS

0

1000

2000

3000

4000

5000

6000

7000

8000

44190 44200 44210 44220 44230 44240

Raman Q1(4.5) and Q

1(10.5)

Probe R1(4.5) and Q

1(10.5)

Pu 16 St 22 Pr 0.85

Pu 32 St 22 Pr 0.85

Pu 64 St 22 Pr 0.85

Cou

nts



ConclusionsConclusions

• Density matrix model for NO ERE CARS developed for both scanning and broadband ERE CARS.

• Theoretical spectra are in good agreement with experiment except for probe scans with high pump and Stokes powers.

• Multimode laser models for the Stokes and UV probe beams appear to give good results for the broadband Stokes ERE CARS process.


Future WorkFuture Work

• Comparison of NO measurements by ERE CARS and LIF in high-pressure counterflow flames – the high-pressure flame facility at Purdue needed some extensive modification, should be operational this spring.

• Incorporation of the AC Stark effect in the density matrix code.

• Investigation of saturation and Stark effects for broadband Stokes ERE CARS.


DNI Modeling of Broadband Stokes ERE CARS in Nitric Oxide

DNI Modeling of Broadband Stokes ERE CARS in Nitric Oxide

0.0

2.0 10-5

4.0 10-5

6.0 10-5

8.0 10-5

-20 -10 0 10 20

BB ERE CARS

BB ERE CARS + Nres FWM

ER

E C

AR

S S

ign

al (

arb

. un

its)

Signal Frequency (cm-1)

Raman Q1(4.5)

Probe R1(4.5)

Raman Q1(10.5)

Probe Q1(10.5)


NO Measurements in Nonpremixed Counterflow Flames

NO Measurements in Nonpremixed Counterflow Flames

Seeded YAGPro 290

Dye Laser

Dye Laser

UnseededYAG

Powerlite9010

SPEX 1000M

PMT

355 nm

704 nm

532 nm

236 nm

591 nm

/2

/2

/2

Filters

Pol.@60

Pol.@60

Pol.@0

Joule Meter

Pol.@-30

WEX

L3

L1

L2

Counter-flow FlameFuel and oxidizer nozzles separated by 20 mm

Fuel = H2

Oxidizer = air or O2

Fuel or Oxidizer Diluents = N2,

CO2


• Pump, Stokes and probe beam energies were 60 mJ/pulse, 40 mJ/pulse, and 1.2 mJ/pulse, respectively in the probe volume; beam waists ~200 m

• 1-meter spectrometer with blazed grating (3600 gr/mm) was used to isolate the signal which was recorded using a back-illuminated CCD imaging camera (Andor Technology Model DU440-BU)

• Spectrometer’s spectral dispersion = 0.146 cm-1 /pixel

• H2/Air Flame measurements were made with 1 mm spatial resolution

Broadband Vibrational ERE-CARS System Experimental Parameters

Broadband Vibrational ERE-CARS System Experimental Parameters


ERE CARS Measurements of NO profiles in Counterflow H2/Air Flame

ERE CARS Measurements of NO profiles in Counterflow H2/Air Flame


Comparison of Experimental and Calculated NO Concentration Profiles in H2 / Air counter-flow

flames with dilution of H2 with either N2 or CO2

Comparison of Experimental and Calculated NO Concentration Profiles in H2 / Air counter-flow

flames with dilution of H2 with either N2 or CO2

N2 10% CO2

N2 25% CO2

N2 35% CO2

480 ppm

420 ppm

300 ppm

200 ppm

180 ppm

80 ppm


Statistics of Single-Shot NO ERE CARS Measurements in the Counterflow H2/Air Flame:

Q1(19.5) Line, 10.7 mm from Fuel Nozzle

Statistics of Single-Shot NO ERE CARS Measurements in the Counterflow H2/Air Flame:

Q1(19.5) Line, 10.7 mm from Fuel Nozzle


Broadband Pure Rotational NO ERE CARS

Broadband Pure Rotational NO ERE CARS

Vibrational ERE CARS

Pure Rotational ERE CARS


Pure Rotational NO ERE CARSPure Rotational NO ERE CARS


Polarization arrangement of pump (ω1), probe (ω3), Stokes (ω2) and the resulting signal beam

(ω4) for Pure Rotational CARS


• For pure rotational CARS (without Electronic Resonance)– 355 nm UV beam with FWHM approx. 0.003 cm-1 , was used as

probe beam

– a 532 nm beam was used to pump the broadband Stokes beam at 591 nm which was split into 2 parts. FWHM of 591 nm beam was 300 cm-1 with energy of about 30 mJ/pulse for each beam

– Measurements were made with varying ratios of NO and N2 in a pressure vessel 6 cm in diameter and 25 cm long

• For pure rotational ERE CARS – the probe beam was at 226 nm with energy < 1mJ /pulse with

FWHM approx. 0.1 cm-1

– the two 591 nm beams were combined and the resulting beam had approx. 50 mJ/pulse at the probe volume

Pure Rotational CARS/ERE-CARS System Experimental Parameters

Pure Rotational CARS/ERE-CARS System Experimental Parameters


Pure Rotational NO CARSPure Rotational NO CARS

0

0.2

0.4

0.6

0.8

1

1.2

20 40 60 80 100 120 140 160 180

Nor

mal

ized

CA

RS

Sig

nal

Raman Shift (cm-1)

21/2

NOS(9.5)S(7.5)S(5.5)S(3.5) S(11.5) S(13.5) S(15.5) S(17.5) S(19.5)

S(9.5)S(7.5)S(5.5)S(3.5) S(11.5) S(13.5) S(15.5) S(17.5) S(19.5) 23/2

NO

T = 300 K P = 13.98 psi

• Stokes beam with FWHM 300 cm-1 covers numerous Raman transitions.

• Probe beam wavelength of 355 nm at spectral dispersion of 0.059 cm-1 /pixel.


Pure Rotational N2 CARSPure Rotational N2 CARSProbe Wavelength = 355 nm

0

0.2

0.4

0.6

0.8

1

1.2

20 40 60 80 100 120 140 160 180

Nor

mal

ize

d C

AR

S S

igna

l

Raman Shift (cm-1)

T = 300 K P = 13.89 psi

S(8) S(10) S(12) S(14) S(16) S(18) S(20)S(6)S(4)S(2)


Pure Rotational NO+N2 CARSPure Rotational NO+N2 CARS

0

0.2

0.4

0.6

0.8

1

1.2

1.4

20 40 60 80 100 120 140 160 180

Nor

mal

ized

CA

RS

Sig

nal

Raman Shift (cm-1)

S(8) S(10) S(12) S(14) S(16) S(18)S(6)S(4)S(2)N

2

78.97% NO and 21.03% N2

P = 13.81 psi

21/2

NOS(9.5)S(7.5)S(5.5)S(3.5) S(11.5) S(13.5) S(15.5) S(17.5) S(19.5)

S(9.5)S(7.5)S(5.5)S(3.5) S(11.5) S(13.5) S(15.5) S(17.5) S(19.5) 23/2

NO

• Significant overlap between the NO and N2 pure rotational spectra. We expected this to provide real time, in-situ reference to get NO/N2 concentration ratio along with

temperature in flames.


Two-Beam Pure Rotational ERE CARSTwo-Beam Pure Rotational ERE CARS



Probe Wavelength = 226.317 nm, 1% NO in Ar

0

5000

10000

15000

40 60 80 100 120 140

Cou

nts

Raman Shift (cm-1)

1% NO in ArRaman S1(12.5)

Probe = 226.320 nmP

1(14.5) = 226.317 nm



0.0

2.0 103

4.0 103

6.0 103

8.0 103

1.0 104

1.2 104

1.4 104

1.6 104

20 40 60 80 100 120 140 160 180

Co

unts

Raman Shift (cm-1)

1% NO in N2 probe wavelength 226.345 nm

S(8) S(10) S(12) S(14) S(16) S(18) S(20)S(6)S(4)S(2)

Raman S1(10.5) Probe P

1(12.5)

21/2

NO

Raman Shift = 80.23 cm-1 for S1(10.5)

Probe Frequency = 44180.26 cm-1 for P1(12.5)

N2



0.0

5.0 103

1.0 104

1.5 104

2.0 104

2.5 104

3.0 104

20 40 60 80 100 120 140 160 180

Co

unts

Raman Shift (cm-1)

S(8) S(10) S(12) S(14) S(16) S(18) S(20)S(6)S(4)S(2)

Raman S1(10.5) Probe P

1(12.5)

21/2

NO

Raman Shift = 80.23 cm-1 for S1(10.5)

Probe Frequency = 44180.26 cm-1 for P1(12.5)

0.3% NO in N2 probe wavelength 226.345 nm

N2

ning chai and robert p. lucht purdue university, west lafayette, indiana 47907 sukesh roy

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