Carbon Nanotube Formation:
C2 Swan Band EmissionsFor Various Ablation Laser Combinations
Carmen RangeLeTourneau University
Longview, TX
NASA Johnson Space CenterThermal Branch
Structures and Mechanics DivisionEngineering Directorate
Increase Production of Carbon Nanotubes
Understand the chemical mechanism
modify current methods or design new methods
Laser Ablation
target
tube
Previous Work
Laser Sample
Optics
Detector
Based on Laser Induced Fluorescence
C2 LIF
Previous ResultsC2 LIF
473.0 473.1 473.2 473.3 473.4 473.5 473.6 473.7 473.8
Wavelength (nm)
Previous ResultsNi LIF
225.0 225.2 225.4 225.6 225.8 226.0
wavelength (nm)
Experimental Setup
Ablation LasersGraphiteTarget
Various combinations involving 3 ablation lasers
Emission Collected by a Fiber Optic
Monochromator disperses emmision onto an ICCD
' = 0
1
2
' = 0
1
2
3
4
20023 cm-1
0 cm-1
C2 Energy Levels
d3g
a3u
X1u+
Vibrational BandsVibrational Bands
Vibrational Bands
Δv = 0Δv = 0
Baseline Variations
Baseline VariationsBaseline Variations
File Lasers Modified Fit Unmodified Fit00jan21e 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
Baseline Variations
Trends in TemperatureTrends in Temperature
Trends in Temperature
Temperature FitsTemperature Fits
Temperature FitsTemperature Fits
File Lasers Delay Slit Width Ratio of Δv = 1 & 0
Ratio of Δv = 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
Temperature Fits
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.
Future Work
• Further analysis of the 3 laser spectra.
• Analysis of data from Parametric Studies.
• Computational modeling for:– nanotube behavior and properties
– molecular intermediates
Acknowledgement
Carl ScottSivaram ArepalliWilliam HolmesPasha Nikolaev
Brad Files
SFF NASA-ASEE
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