In situ conduction ESR and theoretical studies of graphite intercalation by nitric acid

Abstract

Results of an in situ conduction electron-spin resonance (CESR) study of HNO3 molecule intercalation into highly oriented pyrolytic graphite (HOPG) plate with width being comparable with the graphite skin-depth governed by the c-axis conductivity are presented. The changes in the graphite CESR signal line shape, intensity and linewidth and the stepwise changes both of intensity and linewidth of CESR signal of intercalated sample were clearly detected during this reaction. Under the assumption that the graphite CESR signal evolution is caused by the advance of a boundary separating the intercalated and nonintercalated HOPG, the average value of spin reorientation probability during the collision of current carriers with this interface and the diffusion coefficient of nitric acid into the HOPG plate were extracted from experimental data. With the chemical potential versus intercalation time proposed by the authors for the experimental conditions, the stepwise changes of the CESR signal intensity of intercalated sample was calculated theoretically.