Dissociation energy of the ch radical

Abstract

The 4300-Å band of CH has been observed in emission using a carbon furnace above 2400°C which contains 1 atm of Ha gas. From the CH emission intensity variation with temperature and a thermochemical cycle involving the heat of sublimation of graphite, a CH dissociation energy of 80±5 kcal (3.5±0.2 eV) is derived for the*n state. The close agreement between this value and that obtained previously from a CH rotational predissociation, establishes not only that the CH dissociation energy is 80.0 kcal (3.47 eV) but further confirms that the heat of sublimation of graphite is 169.58 kcal. For this 2n state the atomic dissociation products are identified experimentally as ground-state C(3P) and H(2S) atoms. In addition, for the process C2H2 = 2CH an acetylene dissociation energy of 228.1 kcal is derived.