Top: branching to various decay channels of the c′(v′ = 0) excited-state of N₂ as a function of total rotational quantum number, J. The figure includes spontaneous emission to several non-dissociative ground state vibrational levels (v′′ = 0,1 and 2) and decay due to predissociation (dis.). Bottom: fractional population of the N₂ ground state in its lowest vibrational level as a function of J and for several excitation temperatures. The 2:1 ratio of populations for even:odd J levels arises from the combined rotational and nuclear spin statistics.