An application of the Stern-Gerlach experiment to the study of active nitrogen

Many theories have been put forward at one time or another to explain the chemical activity of “active nitrogen” and the mechanism of the production of the yellow “after-glow.” Reunion of nitrogen atoms to form molecules, metastable molecules and interactions between atoms and molecules have all been drawn upon to explain the after-glow. At the time the work described in the present paper was commenced the theory holding the field was that of Sponer. According to this theory two normal nitrogen atoms collide in a triple collision with a normal nitrogen molecule with the resultant formation of one normal nitrogen molecule and one excited molecule. Since the carrier of the after-glow is known to be an excited nitrogen molecule with about 11⋅5 volts energy, and since the dissociation energy was then believed to be 11⋅5 volts, the theory seemed to explain the energy relations of active nitrogen satisfactorily. The comparative rareness of such a triple collision was in agreement with the long life of the after-glow. On this theory the chemical activity would be attributed to the nitrogen atoms (in their ground state). A support for this theory would have been obtained if it could have been shown that nitrogen atoms in their ground state, which is known to be a 4S state, are present in active nitrogen. Later work has, however, shown that the dissociation energy of the nitrogen molecule is about 9⋅1 volts and not 11⋅5 volts as supposed by Sponer, and hence the theory cannot be valid.