**Introduction**

Currently the major goals in the area of space electronics for NASA are
to make them ever smaller and radiation-hard. Currently, space
electronics are based on silicon, but unfortunately, silicon is not
radiation hard. Due to their nanometer-scale size, purported stability,
well-documented high conductivity and Young\'s modulus, carbon nanotubes
may be ideally suited to applications in space electronics. Hence, the
purpose of this project is to examine the effect of ionized radiation on
the mechanical and electronic properties of carbon nanotubes and
determine their suitability to space applications. Results from samples
grown at the University of Michigan in an inductively coupled plasma
(ICP) system, CNTs produced at NASA and

Tubes@ Rice which are known single-walled carbon nanotubes, will be
compared in this paper.

**Methods**

The carbon nanostructures were produced at the University of Michigan by
placing a Si wafer onto which 10-20 nm of Fe were laser ablated, inside
the ICP system for approximately five and a half hours. The plasma
contained 87% Argon, 6.5% Methane and 6.5% Hydrogen. The carbon
nanotubes from NASA were produced using the DC arc-discharge method and
cleaned using the cleaning process developed by Dr. Benavides.
Tubes@Rice, which are single-walled carbon nanotubes are from Rice
University. They were produced by Dr. Smalley's group via laser
vaporization of graphite as described in their 1995 paper[^1].

These samples have thus far been examined prior to radiation using
Transmission Electron Microscopy (TEM) and micro-Raman Spectroscopy (at
514.5 nm). For Transmission Electron microscopy, a Hitachi-800
Transmission Electron Microscope (200 KeV, .00251 nm wavelength) was
used. The Micro-Raman system was consists of an Argon-ion laser,
monochromator, photo-multiplier tube (PMT) and optical microscope set-up
in back-scattered configuration

# Results

![](media/image1.png){width="3.1444444444444444in"
height="1.9236111111111112in"}

Figure 1: Carbon nanotubes grown at NASA Goddard Space Flight Center

(DC-arc discharge method, bar = 400 nm)

![](media/image2.wmf){width="4.134027777777778in"
height="2.672222222222222in"}

Figure 2: Raman of NASA sample A04 in Tangential mode region @ 514.5 nm
deconvoluted using PeakFit with Gaussian Peak Amplitudes

![](media/image3.wmf){width="4.179166666666666in"
height="2.720833333333333in"}

Figure 3: Raman of NASA sample A06 in Tangential mode region @ 514.5 nm
deconvoluted using PeakFit with Gaussian Peak Amplitudes

![](media/image4.wmf){width="4.397916666666666in"
height="2.852777777777778in"}

Figure 4: Raman of NASA sample A07 in Tangential mode region @ 514.5 nm

![](media/image5.png){width="1.8430555555555554in"
height="1.6256944444444446in"}

Figure 5: TEM of single carbon nanostructure grown in ICP system (bar =
40 nm)

![](media/image6.jpeg){width="1.9256944444444444in"
height="1.426388888888889in"}

Figure 6: TEM of lower portion of the above carbon nanostructure (bar =
25 nm)

![](media/image7.wmf){width="4.586111111111111in" height="2.975in"}

Figure 7: Raman of wafer containing carbon nanostructures above in
Tangential mode region @ 514.5 nm deconvoluted using PeakFit with
Lorentzian peak amplitudes

![](media/image8.png){width="2.09375in" height="1.7520833333333334in"}

Figure 8: TEM of Tubes@Rice (bar = 40 nm)

![](media/image9.wmf){width="4.415972222222222in"
height="3.0194444444444444in"}

Figure 9: Raman of Tubes@Rice in the Tangential Mode Region at 514.5 nm

![](media/image10.wmf){width="4.247222222222222in"
height="2.7645833333333334in"}

Figure 10: Raman of Tubes@Rice deconvoluted using PeakFit with
Lorentzian Peak Amplitudes

**Discussion and Future Work**

Currently, as can be seen by comparing the Raman results (prior to
exposure to radiation) of the NASA samples with that of Tubes@Rice,
while the NASA samples show promise, whether they are single or
multi-walled carbon nanotubes cannot be determined at the 514 nm
wavelength. These samples clearly need to be examined at the 633 nm
wavelength with a Helium-Neon laser, which provides for better coupling
and examination of the radial breathing modes. The TEM micrographs
provide some insight into the average dimensions of the nanotubes as
well as to their crystallinity. However, whether the CNTs are
multi-walled or single-walled must be determined using HR-TEM. Also, the
irradiation of the NASA samples, Tubes@Rice and the samples grown with
ICP at the University of Michigan, is expected to be done early this
year.

# Acknowledgements

Many thanks are owed to the following people:

Dr. Jeannette Benavides of the NASA Goddard Space Flight Center, who
generously donated her time, provided excellent guidance, and stepped me
through her cleaning process.

Mr. Harry Shaw, my mentor, of the NASA Goddard Space Flight Center who
provided sound advice at various junctures in this project.

Ms. Shavesha Anderson of the NASA Goddard Space Flight Center, who
taught me how to use the carbon arc welder and other equipment, and
introduced me to other people at the center who were very helpful.

Mr. Fred Felt of the NASA Goddard Space Flight Center, who taught me how
to use the StereoScan 38FE scanning electron microscope.

Dr. Reginald Ronningen and Dr. Al Zeller, whom in the coming months will
be operating the ion source and irradiating the carbon nanotubes and
have already given a significant amount of time to this project.

Dr. Virginia Ayres, my major professor, who generously shared her time
and expertise in SPM portion of the project

Last but not least, Dr. Martin Crimp, associate professor in the ChEMSM
Department at Michigan State University, who generously donated his time
as well as "microscope time" on his TEM

[Effects of Ionized Radiation on the Mechanical and
Electronic]{.underline}

[Properties of Carbon Nanotubes]{.underline}

Summer 2002 JPFP Mini-Grant Project Report

By: Susan Song

[^1]: \"Catalytic Growth of Single-Walled Nanotubes by Laser
    Vaporization.\" T. Guo, P. Nikolaev, A. Thess, D. T. Colbert and R.
    E. Smalley. Chemical Physics Letters, **243**, 49-54 (1995).