Methane (CH4) adsorption and isothermal hydrogen (H2) desorption kinetics on a C(001)–(1×1) surface have been investigated by observing the surface hydrogen coverage θH which is estimated from the electron‐stimulated desorption yield of H+ ions. The time evolution of θH under CH4 exposure, in pressure and temperature ranges of 1×10−8–5×10−7 Torr and 600–800 °C, reveals that the CH4 adsorption is a first‐order reaction. The isothermal H2 desorption is conducted in a temperature range of 1095–1270 °C. The time evolution of θH shows that the isothermal H2 desorption is also a first‐order reaction. From Arrhenius plots of the reaction coefficients, the activation energies of CH4 adsorption and H2 desorption are evaluated to be 7.3±1.7 and 21±4.9 kcal/mol, respectively. Atomistic kinetics model for CH4 adsorption and H2 desorption are discussed, especially in connection with a recent finding of gas source molecular beam epitaxy of diamond (001) with pure CH4 without any hydrogen or oxygen radicals.

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