title: Cryogenic-temperature electron microscopy direct imaging of carbon nanotubes and graphene solutions in superacids.
abstract: Cryogenic electron microscopy (cryo-EM) is a powerful tool for imaging liquid and semiliquid systems. While cryogenic transmission electron microscopy (cryo-TEM) is a standard technique in many fields, cryogenic scanning electron microscopy (cryo-SEM) is still not that widely used and is far less developed. The vast majority of systems under investigation by cryo-EM involve either water or organic components. In this paper, we introduce the use of novel cryo-TEM and cryo-SEM specimen preparation and imaging methodologies, suitable for highly acidic and very reactive systems. Both preserve the native nanostructure in the system, while not harming the expensive equipment or the user. We present examples of direct imaging of single-walled, multiwalled carbon nanotubes and graphene, dissolved in chlorosulfonic acid and oleum. Moreover, we demonstrate the ability of these new cryo-TEM and cryo-SEM methodologies to follow phase transitions in carbon nanotube (CNT)/superacid systems, starting from dilute solutions up to the concentrated nematic liquid-crystalline CNT phases, used as the 'dope' for all-carbon-fibre spinning. Originally developed for direct imaging of CNTs and graphene dissolution and self-assembly in superacids, these methodologies can be implemented for a variety of highly acidic systems, paving a way for a new field of nonaqueous cryogenic electron microscopy.
authors.affiliation: Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: O
authors.initials: O
authors.lastname: Kleinerman
authors.affiliation: The Richard E. Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas, U.S.A.
authors.forename: A Nicholas G
authors.initials: AN
authors.lastname: Parra-Vasquez
authors.affiliation: The Richard E. Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas, U.S.A.|Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, U.S.A.
authors.forename: M J
authors.initials: MJ
authors.lastname: Green
authors.affiliation: The Richard E. Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas, U.S.A.
authors.forename: N
authors.initials: N
authors.lastname: Behabtu
authors.affiliation: Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: J
authors.initials: J
authors.lastname: Schmidt
authors.affiliation: Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Kesselman
authors.affiliation: The Richard E. Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas, U.S.A.
authors.forename: C C
authors.initials: CC
authors.lastname: Young
authors.affiliation: Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Cohen
authors.affiliation: The Richard E. Smalley Institute for Nanoscale Science and Technology, Rice University, Houston, Texas, U.S.A.|Department of Chemical & Biomolecular Engineering and Chemistry, Rice University, Houston, Texas, U.S.A.|Department of Materials Science & NanoEngineering, Rice University, Houston, Texas, U.S.A.
authors.forename: M
authors.initials: M
authors.lastname: Pasquali
authors.affiliation: Department of Chemical Engineering and the Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Y
authors.initials: Y
authors.lastname: Talmon
keywords: Carbon nanotubes; controlled environment vitrification system; cryo-SEM; cryo-TEM; specimen preparation; superacid