Secondary Electron Emission of Pyrolytic Graphite Cleaved in a High Vacuum

Pyrolytic graphite was cleaved in a high vacuum to obtain clean surfaces, and the secondary electron emission properties of these surfaces were determined. Pyrolytic graphite has a maximum secondary emission yield of 1.0 at 300-eV primary electron energy for electrons incident normal to the basal plane. The most probable energy of the emitted secondaries is 2 eV, with one-half of the secondaries having energy in excess of 8 eV. A maximum secondary emission yield of 0.75 at 350-eV primary energy was measured for normal incident electrons on a face that was perpendicular to the basal plane. The backscattered fraction for pyrolytic graphite was found to be 0.05. No differences were observed in the secondary electron emission properties of single-crystalline pyrolytic graphite and pyrolytic graphite that was less well ordered.