The process of driving out of sulfuric acid from a carbon by heating in vacuum was tracked by ESR measurements. There is a sudden dramatic increase in width of the ESR line, followed by a somewhat slower decrease; the tip of the peak coinciding with the beginning of the driving-out process (-200Β°C). Some molecular relocations with increase in ionization occur before that stage. The peak corresponds to a kinetic type process occurring in the residual part of the compound. A second broad peak is observed at higher temperature (-500-6Oo"C), which seems to reflect some rearrangements taking place when an over abundance of acid is present at the start of the process (lamellar compound?).
15, Electron spin resonance in glassy carbon S. Orzeszko* and K. T. Yang? (&z&n Research ~~~~, State Un~v~s~ of New York at aunt, BuJ&zlo, New York). ESR was investigated for a series of samples of glassy carbon heat treated to various temperatures in the range lOOO-3200Β°C. For the solid material, the width shows a shallow minimum at around HTT 1600% but then greatly increases above HTT 2600Β°C. For a ground material, a large broadening in the transition range is observed. The intensity passes through a minimum at HTT 1200Β°C and increases to a strong maximum at around HTT 1600% after which it decays (above HTT 1200Β°C) to a value corresponding to concentration of conduction carriers (0*5 X 1019 spin/g). The effects of neutron irradiation and of subsequent anneal also have been studied. The irradiated material shows a large broadening in the transition range (-1300Β°C) similar to the broadening observed for irradiated soft carbons.