http://bjm.scs.uiuc.edu 23 June 2009

Performance of a Continuous Performance of a Continuous Supersonic Expansion Discharge Supersonic Expansion Discharge

Source Evaluated by Laser-Induced Source Evaluated by Laser-Induced Fluorescence SpectroscopyFluorescence Spectroscopy

Kyle N. Crabtree, Carrie A. Kauffman, and Benjamin J. McCall

23 June 2009McCall Research Group

University of Illinoishttp://bjm.scs.uiuc.edu

http://bjm.scs.uiuc.edu 23 June 2009

OverviewOverview

Intro/Motivation Experimental Layout Spectroscopic Efforts Current Measurements

http://bjm.scs.uiuc.edu 23 June 2009

Supersonic Expansion Supersonic Expansion Discharge SourceDischarge Source

Operational lifetime: >100 hrs

Typical Voltage: 200-500 V

Typical Current: ~30 mA

Typical Pressure: 1-3 atm

http://bjm.scs.uiuc.edu 23 June 2009

Source OptimizationSource Optimization

Pressure Composition Diameters Lengths Diameter Ratio Voltage/Current Polarity Size Geometry Material Size Geometry

http://bjm.scs.uiuc.edu 23 June 2009

LIF SpectroscopyLIF Spectroscopy

Generate 2D map of ion temperature and relative density

1. Optimize spectrometer using I2

2. Make map using N2+

3. Vary source parameters, and repeat

4. Investigate larger, more complex ions

http://bjm.scs.uiuc.edu 23 June 2009

OverviewOverview

Intro/Motivation Experimental Layout Spectroscopic Efforts Current Measurements

http://bjm.scs.uiuc.edu 23 June 2009

Experimental LayoutExperimental Layout

Nd:YVO4

PMTComputer

Laser Locking/Scanning

Electronics

DAQ

Lock-inAmplifier

899-29Ring Dye Laser

λ-meter

Optical Chopper

I2Cell

High-VoltagePower Supply

N2

I2OpticalFilter(s)

http://bjm.scs.uiuc.edu 23 June 2009

CFN899 AutoscanCFN899 Autoscan

LaserPower

Long & Short Vernier Etalons

Thin Etalon

Scan Drive

I2 CellAbsorption

Vernier Etalons

http://bjm.scs.uiuc.edu 23 June 2009

OverviewOverview

Intro/Motivation Experimental Layout Spectroscopic Efforts Current Measurements

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Molecular IodineMolecular Iodine

B3Π0+

u – X1Σg+ (6-0), (8-1), (10-2), and

(12-3) vibronic transitions at 608 nm

Sample Spectrum Here Boltzmann Plot Here

)

http://bjm.scs.uiuc.edu 23 June 2009

T.A. Miller, T. Suzuki, E. Hirota J. Chem. Phys. 80, (1984) 4671-4678.

NN22++

A2Πu – X2Σg+ (4-0)

Meinel Band transition (614 nm)

LIF characterization by T.A. Miller et al. in 1984

2Π3/22Π1/2

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Source EmissionSource Emission

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OverviewOverview

Intro/Motivation Experimental Layout Spectroscopic Efforts Current Measurements

http://bjm.scs.uiuc.edu 23 June 2009

Spectroscopy of HSpectroscopy of H33++ ((νν22 0) 0)

(ortho) (para) (para) (ortho)

J

500

0

0 1 2 3

E(c

m-1)

K

3

2

1

0

R(1,0) R(1,1)

64 cm-1

169 cm-1

315 cm-1

237 cm-1

87 cm-1

R(2,1) R(2,2) R(3,3)

http://bjm.scs.uiuc.edu 23 June 2009

Difference Frequency LaserDifference Frequency LaserMgO-doped PPLN crystalSpectral Coverage: 2.2 – 4.8 μmPower: ~350 μW

11

2

2

http://bjm.scs.uiuc.edu 23 June 2009

Summary/Future DirectionsSummary/Future Directions

Design and construction of source Iodine rotational temperature: 8 K Cavity ringdown spectroscopy of H3

+ with difference frequency laser

Future work: temperature measurements of larger ions

Integration with SCRIBES

http://bjm.scs.uiuc.edu 23 June 2009

AcknowledgementsAcknowledgements

University of Illinois SCS Machine Shop

Bill Knight Christopher Neese McCall Research

Group

http://bjm.scs.uiuc.edu 23 June 2009

Cavity Ringdown Cavity Ringdown SpectroscopySpectroscopy