On the Dissociation Energy of Carbon Monoxide and the Heat of Sublimation of Carbon

None of the values of the dissociation energy of carbon monoxide, D(CO), proposed on the basis of interpretations of predissociations in the spectrum of CO is in satisfactory agreement with the results of electron-impact experiments. The only possible interpretation of these experiments gives D(CO)=9.6 ev. Compelling reasons can be given for considering this result of sufficient accuracy to make it irreconcilable with any of the values from the band spectrum. A new interpretation of the effects in the spectrum which brings agreement with the electron impact value is possible, however. It involves a potential curve with maximum for $J=0$ for the state a^'³Σ⁺ of CO which predissociates B¹Σ⁺ and b³Σ⁺ at 11.11 ev. Various data favor this interpretation and its consequences. Satisfactory agreement among all data bearing on D(CO) and L₁(C), the heat of sublimation of carbon, can be attained in this way.