Advances in Chemical Engineering and Science, 2013, 3, 7-9
http://dx.doi.org/10.4236/aces.2013.33A3003 Published Online August 2013 (http://www.scirp.org/journal/aces)
Noble Interactions between Ar and Carbons
Mitsunori Furuya, Ayaka Yanagitsuru, Kenji Ichimura
Graduate School of Science and Technology, Kumamoto University, Kumamoto, Japan
Received May 10, 2013; revised June 10, 2013; accepted July 10, 2013
Copyright © 2013 Mitsunori Furuya et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Noble interactions between Ar and carbons are observed for carbons, such as carbon nanotubes and carbon blacks by
means of mass-analyzed thermal desorption. The absorption states exist at around 300 K as well as at around 100 K.
X-ray photoelectron spectroscopy reveals that Ar2p shows the chemical shifts. These results suggest that Ar is in charge
and it is in valence state, or gives the evidence of the chemical interaction.
Keywords: Ar; Interaction; Carbon; Valence States
The compounds of rare gas elements such as Kr and Xe
have been reported [1-5].
The examinations of compressibility for C60 using He,
Ne and Ar as pressure media and the study of diffusion
kinetics in solid C60 have been carried out under the con-
ditions of high pressure at around several kbar [6-9]. In
these, the chemical interactions have not been discussed.
We have reported the chemical interactions of rare
gases , such as He, Ne and Ar, in solid carbon nano-
tubes. Closed carbon nanotubes (CNTs) show larger
amounts of absorption for gases such as hydrogen, He,
Ne and Ar than opened CNTs. From these results, we
conclude that sites that are preferentially found in end-
caps provide more active electronic states for the chemi-
cal interaction between rare gases and solid carbon na-
This paper presents results on the thermal desorption
from carbon blacks and the X-ray photoelectron spectra
C60 (Hoechst, 99.98% purity) was used without further
Endcaps and endcaps-opened multi wall carbon nano-
tubes (CMWCNT and OMWCNT, Bucky USA BU-200
and 201, 3 - 10 multi-layer with 2 - 10 nm diameter and 3
- 30 μm length), endcaps and endcaps-opened single wall
carbon nanotubes (CSWCNT and OSWCNT, Bucky
USA BU-202 and 203, 1.4 - 3 nm diameter and 10 - 50
μm length) were used without further purification. As for
the single and multi-wall carbon nanotubes, there is the
only difference in the both end structure, and the another
structure is the same.
Carbon black (Seast 3HAF (S3)) and graphitized car-
bon blacks (3855, 3845 and 3800) were supplied from
Tokai Carbon Co. Table 1 shows the characterizaion of
After vacuum heating at 653 K or 1073 K, samples
were exposed to Ar (Nippon Sanso, >99.99% purity) of 1
to 1.4 atm, at 473 K for 1 to 10 days. After the sample
wascooled to liquid nitrogen temperature, the sample
tube was evacuated to ultra-high vacuum. In-situ meas-
urements of the thermal desorption with the tempera-
ture-rise rate of 5 K/min and X-ray photoelectron spectra
by using MgK α were carried out.
3. Results and Discussion
Figures 1 and 2 show the thermal desorption of Ar from
The Ar desorption peaks were observed at around 90 -
100 K in the lower temperature region for all carbon
blacks. These peak temperatures were higher than that of
boiling point of Ar such as 87 K. Therefore, these results
Table 1. Characteristics of carbon blacks.
Sample Particle radii/nm
N2 specific surface
Seast 3HAF (S3)28 79
3855 25 90
3845 40 57
3800 70 27
opyright © 2013 SciRes. ACES
M. FURUYA ET AL.
Figure 1. Thermal desorption of Ar from carbon blacks,
3800 and 3845.
Figure 2. Thermal desorption of Ar from carbon blacks,
3855 and S3.
suggest the stronger interaction than van der Waals in-
In addition, the Ar desorption peaks were observed at
around 350 K in the higher temperature region than room
temperature. Therefore, these results suggest the chemi-
cal interaction between Ar and carbon blacks.
Figure 3 shows the X-ray photoelectron spectra of
Figure 3. The x-ray photoelectron spectra of Ar2p for C60,
graphite and closed and open multiw all carbon nanotu bes.
Ar2p for C60 and closed and open multiwall carbon na-
notubes exposed to Ar gas at around room temperature,
and the Ar+-sputtered graphite.
The peaks appeared at around 275 eV are assigned to
the peaks due to the X-ray impurities.
For Ar+-sputtered graphite, Ar2p1/2-Ar2p3/2 peaks were
observed. This spin-orbit interaction indicates that Ar
exists as the neutral molecule in the graphite. On the other
hand, for C60, Ar2p peak was not observed at around 241
eV and the peak appears at around 269 eV, showing the
large chemical shift to that for the Ar+-sputtered graphite
at around 241 eV. The spin-orbit interaction was also not
For the closed and open multiwall carbon nanotubes,
although the signal intensities were weak, Ar2p peaks
were observed at around 264 eV, showing also the large
chemical shift to that for the Ar+-sputtered graphite at
around 241 eV.
Figure 4 shows the X-ray photoelectron spectra of
Ar2p for the Ar+-sputtered carbon blacks. Although cha-
racteristics of the thermal desorption were different from
amorphous-type carbon black and graphitized carbon
blacks, the Ar2p peaks were observed at around 242 and
244 eV. The spin-orbit interaction was observed for the
For the Ar+-sputtered graphite, the difference between
C1s and Ar2p3/2 was observed as 43.3 eV, and the split-
ting width of the spin-orbit interaction was 2.2 eV. For
carbon blacks, the difference between C1s and Ar2p3/2
Copyright © 2013 SciRes. ACES
M. FURUYA ET AL.
Copyright © 2013 SciRes. ACES
Figure 4. The X-ray photoelectron spectra of Ar2p for car-
was observed as 42.6 ± 0.1 eV, and the splitting width of
the spin-orbit interaction was 3.0 eV. By the comparison
with the Ar+-sputtered graphite, the difference between
C1s and Ar2p3/2 became to be lower and the splitting
width of the spin-orbit interaction increased for the car-
bon blacks. These results indicate that the ad-/ab-sorption
states observed at around 90 - 100 K and 350 K are due
to the weak and strong chemical interactions.
Carbons show the noble interaction with Ar due to the
characteristic structures and those electronic states. The
X-ray photoelectron spectroscopy results in the chemical
interaction between Ar and carbons such as C60, CNTs,
and carbon blacks. Carbons have possibilities of the di-
versity of chemical interactions with designs of structure
and those electronic states.
Authors thank Tokai Carbon Co. for the sample supply
of the carbon blacks. Authors also acknowledge Profes-
sor M. Koinuma of Kumamoto University for the support
of XPS measurements for the Ar+-sputtered carbon
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