Dissociation Energy of the CO Molecule and the Sublimation Heat of Carbon

Abstract

IN the letter above, which I had the opportunity of reading in manuscript form, Goldfinger and Lasareff calculate the heat of dissociation of CO on the basis of thermochemical and spectroscopical data and give as the most probable value 11 v.e. with a possible error of not more than 0.1 v.e. I want to direct attention to the fact that this may be independently checked by the results of the investigation by Schmid and Gerö¹, who observed in addition to the known predissociation in the = 0 level of B¹, occurring at J = 38, another predissociation (breakdown of rotational structure) occurring at J = 18 of the = 1 level. The application of the reasoning of Herzberg² to this case shows that the lower limit of the asymptote of the perturbing electronic level is situated only 40 cm.¹ below the upper limit, equivalent to 11.062 v.e., and that its real position therefore is 11.06 ± 0.005 v.e. This would represent the dissociation energy of CO if the asymptote really corresponds to the dissociation in C(³P) + O(³P). The alternative possibility that it would correspond to dissociation into C(¹D) + O(³P) and that therefore D_CO = 1.105 v.e. will be discussed in detail elsewhere.