What are Nanotubes?

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Carbon Nanotube Formation C2 Swan Band
Emissions For Various Ablation Laser
Combinations Carmen Range LeTourneau
University Longview, TX NASA Johnson Space
Center Thermal Branch Structures and Mechanics
Division Engineering Directorate
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Increase Production of Carbon Nanotubes
modify current methods or design new methods

• Understand the chemical mechanism

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Laser Ablation
target
tube
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Previous Work
Based on Laser Induced Fluorescence
Detector
Optics
Laser
Sample
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C2 LIF
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Previous Results

C2 LIF
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Previous Results
Ni LIF
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Experimental Setup
Monochromator disperses emmision onto an ICCD
Emission Collected by a Fiber Optic
Ablation Lasers
Graphite Target
Various combinations involving 3 ablation lasers
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d3Pg
a3Pu
X1Su
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Vibrational Bands
Vibrational Bands
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Vibrational Bands
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?v 0
?v 0
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Baseline Variations
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Baseline Variations
Baseline Variations
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Baseline Variations
File Lasers Modified Fit Unmodified Fit
00jan21e IR Gr Gr 9600 K 9600 K
00jan6e Gr Gr IR 9600 K 9600 K
99dec20e IR Gr IR 8800 K 8800 K
99dec22f IR IR Gr 8600 K 8800 K
00jan21h IR Gr Gr 8000 K 8300 K
00jan6h Gr Gr IR 7600 K 8100 K
99dec22h IR IR Gr 7900 K 8000 K
00jan6g Gr Gr IR 7800 K 8000 K
00jan21g IR Gr Gr 7800 K 7900 K
99dec22i IR IR GR 7800 K 7900 K
99dec20g IR Gr IR 7700 K 7800 K
99dec20h IR Gr IR 7600 K 7700 K
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Trends in Temperature
Trends in Temperature
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Trends in Temperature
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Temperature Fits
Temperature Fits
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Temperature Fits
Temperature Fits
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Temperature Fits
File Lasers Delay Slit Width Ratio of ?v 1 0 Ratio of ?v 1 -1
00jan21e IR Gr Gr 1500 100 9600 K 6500 K
00jan6e Gr Gr IR 1500 100 9600 K 6300 K
99dec20e IR Gr IR 1500 100 8800 K 6000 K
99dec22f IR IR Gr 1500 100 8800 K 5900 K
00jan21h IR Gr Gr 5000 500 8300 K 5900 K
00jan6h Gr Gr IR 5000 500 8100 K 5900 K
00jan6g Gr Gr IR 5000 100 8000 K 6200 K
99dec22h IR IR Gr 5000 100 8000 K 6400 K
00jan21g IR Gr Gr 5000 100 7900 K 6200 K
99dec22i IR IR Gr 5000 500 7900 K 5800 K
99dec20g IR Gr IR 5000 100 7800 K 6000 K
99dec20h IR Gr IR 5000 500 7700 K 5800 K
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Conclusions

• Different ablation laser combinations result in
  different C2 emmission spectra.
• Shorter wavelength lasers result in spectra with
  greater intensity and warmer temperatures.
• Fitting is complicated by a broad underlying
  contribution of uncertain origin.
• Spectra does not appear to fit well to a single
  temperature.

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Future Work

• Further analysis of the 3 laser spectra.
• Analysis of data from Parametric Studies.
• Computational modeling for
• nanotube behavior and properties
• molecular intermediates

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Acknowledgement

• Carl ScottSivaram ArepalliWilliam HolmesPasha
  NikolaevBrad FilesSFF NASA-ASEE