title: Exploring the radical nature of a carbon surface by electron paramagnetic resonance and a calibrated gas flow.
abstract: While the first Electron Paramagnetic Resonance (EPR) studies regarding the effects of oxidation on the structure and stability of carbon radicals date back to the early 1980s the focus of these early papers primarily characterized the changes to the structures under extremely harsh conditions (pH or temperature)(1-3). It is also known that paramagnetic molecular oxygen undergoes a Heisenberg spin exchange interaction with stable radicals that extremely broadens the EPR signal(4-6). Recently, we reported interesting results where this interaction of molecular oxygen with a certain part of the existing stable radical structure can be reversibly affected simply by flowing a diamagnetic gas through the carbon samples at STP(7). As flows of He, CO2, and N2 had a similar effect these interactions occur at the surface area of the macropore system. This manuscript highlights the experimental techniques, work-up, and analysis towards affecting the existing stable radical nature in the carbon structures. It is hoped that it will help towards further development and understanding of these interactions in the community at large.
authors.affiliation: Chemistry Institute, The Hebrew University of Jerusalem; Biological Chemistry Department, Ariel University.
authors.forename: Uri
authors.initials: U
authors.lastname: Green
authors.affiliation: Chemistry Department, Faculty of Exact Science, Bar Ilan University.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Shenberger
authors.affiliation: Chemistry Institute, The Hebrew University of Jerusalem.
authors.forename: Zeev
authors.initials: Z
authors.lastname: Aizenshtat
authors.affiliation: Biological Chemistry Department, Ariel University; Chemistry Department, Ben-Gurion University.
authors.forename: Haim
authors.initials: H
authors.lastname: Cohen
authors.affiliation: Chemistry Department, Faculty of Exact Science, Bar Ilan University; Sharon.ruthstein@gmail.com.
authors.forename: Sharon
authors.initials: S
authors.lastname: Ruthstein
mesh_terms: D002138:Calibration; D002244:Carbon / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D010100:Oxygen / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D002244:Carbon; D010100:Oxygen