Results of an in situ conduction electron spin resonance study of HNO3 molecule intercalation into narrow highly oriented pyrolytic graphite slabs were presented. The changes in the graphite conduction electron spin resonance signal line shape, intensity and line-width and the step-wise changes both of intensity and line-width of the conduction electron spin resonance signal from the intercalated sample were clearly detected during this reaction. Under the assumption that the graphite conduction electron spin resonance signal evolution was caused by the advance of a boundary separating the intercalated and non-intercalated highly oriented pyrolytic graphite, the constant of two-dimensional diffusion of nitric acid molecules into highly oriented pyrolytic graphite and the average value of the spin reorientation probability during the collision of current carriers with this interface were extracted from the experimental data.

Diffusion and Intercalation of Nitric Acid into Highly Oriented Pyrolytic Graphite: an in Situ Conduction ESR Study. Ziatdinov, A.M., Kainara, V.V., Krivoshei, A.N.: Physica Status Solidi A, 2000, 182[2], 709-15