The Dissociation Energy of Nitrogen

Abstract

IN a recent very interesting letter to NATURE (Sept. 1, p. 313) E. Gaviola reports the occurrence of the NH-band λ3360-70, using Wood's arrangement for the optical excitation of mercury vapour, when nitrogen and hydrogen are admitted. From the fact that the intensity of the band is proportional to the square of the intensity of the exciting light, Gaviola concludes that the atomic nitrogen is formed by three-body collisions of N₂-molecules with two excited mercury atoms. It follows that the dissociation energy of nitrogen is less than 9.8 volts, whereas Sponer (Zeits. f. Phys., 34, 622; 1925), according to her interpretation of the nitrogen afterglow, has calculated the value 11.4 volts. Moreover, the latter value is confirmed by a rough extrapolation of the curve for the frequency of vibration in the normal state of the nitrogen molecule (cf. H. Sponer, Zeits.f. Phys., 41, 611; 1927).