Reaction of thermal atomic hydrogen with carbon

Abstract

The reaction of thermal atomic hydrogen, produced at the surface of a hot tungsten filament, with evaporated carbon films leads to the production of a number of gaseous products. At least 12 have been identified with the largest number of these being cyclic compounds consistent with the structure of graphite. Methane, the major gas phase product (74% partial pressure), is produced with a stoichiometric reaction probability of 0.002. Although the relative reaction rates decrease rapidly with increasing product mass, the total rate of carbon transport is 60% greater than the rate of methane production. Activation energies obtained for 10 of the products by varying the carbon temperature are the same within experimental error. These features are discussed in terms of a highly simplified model of the reaction with the actual reaction following a complicated branching free radical mechanism.