Intercalation of two-dimensional graphite films on metals by atoms and molecules

An analysis is made of some general laws governing a new physical effect, i .e., the spontaneous penetration of particles (atoms, C-60 molecules) adsor bed on a two-dimensional graphite film on a metal (Ir, Re, Pt, Mo, ...) to beneath the graphite film (intercalation). It is shown that atoms having lo w ionization potentials (Cs, K, Na) intercalate a two-dimensional graphite film on iridium at T=300-400 K with an efficiency kappa approximate to 0.5, accumulating beneath the film to a concentration of up to a monolayer. Ato ms having high ionization potentials (Si, Pt, Ni, C, Mo, etc.) intercalate a two-dimensional graphite film on iridium at T approximate to 1000 K with an efficiency kappa approximate to 1, forming beneath the film a thick inte rcalate layer which is strongly bonded chemically to the metal substrate bu t is probably weakly bonded to the graphite monolayer by van der Waals forc es. The presence of a graphite "lid" impeding the escape of atoms from the intercalated state up to record high temperatures T similar to 2000 K leads to superefficient diffusion (with an efficiency close to one) of various a toms (Cs, K) into the bulk of the substrate (Re, Ir). (C) 1999 American Ins titute of Physics. [S1063-7842(99)01609-8].