Two Confined Phases of Argon Adsorbed Inside Open Single Walled Carbon Nanotubes

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DOIResolve DOI: http://doi.org/10.1021/la0358872
AuthorSearch for: ; Search for:
TypeArticle
Journal titleLangmuir
Langmuir
ISSN0743-7463
Volume20
Issue14
Pages59405945; # of pages: 6
AbstractIsothermal adsorption of Ar on single walled carbon nanotubes (SWNTs) has been studied at 77 and 87 K. The SWNTs have been grown by laser vaporization of a graphite pellet containing 0.6% (atomic) Ni/Co catalyst. The nanotubes have been prepared for argon adsorption measurements by prolonged outgassing of as-grown material in a vacuum at room temperature (295 K), at elevated temperatures of up to 475 K, and by oxidization for 2 h in dry air at 470 K. Formation of two condensed phases of Ar in the interior of SWNTs has been observed at 77 K. The low-density phase is formed at 155(5) Torr, while the high-density phase, at 120(5) Torr. At 87 K, only a single phase has been observed at 185(5) Torr. Condensation at both 77 and 87 K appears to be the first-order phase transition. Onset of the quasi-one-dimensional linear (one-channel) phase and the quasi-two-dimensional monolayer (six-channel) phase formation on the external surface of bundles has been observed at 77 K near 0.0017 and 0.8 Torr, respectively, and at 87 K near 0.018 and 5 Torr, respectively. Isosteric heats of adsorption for the one-channel phase, the first external layer, and the second external layer have been determined to be equal to 137, 107, and 70 meV, respectively.
Publication date
AffiliationNational Research Council Canada; NRC Steacie Institute for Molecular Sciences
Peer reviewedNo
Identifier10367391
NPARC number12338892
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Record identifier3d090a9d-9f15-4c92-b042-698efb96e02c
Record created2009-09-11
Record modified2016-05-09
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