New theory of active nitrogen

The details of the collisional quenching of N₂ (B ³Π)ν′₁ are crucial to theories of active nitrogen. It is concluded that quenching of N₂(B ³Π)ν′₁ occurs by transfer to lower energy ν′₂ levels of the ${\mathrm{A\hspace{0.17em}}}^3{\Sigma }_u^{+}$ state but with large rotational energy and that collisional transfer of N₂(A) to N₂(B) also produces high rotational energy in N₂(B). The observed quenching of N₂(B ³Π)ν′₁ corresponds to rapid rotational relaxation and electronic state interchange that appear as fast vibrational relaxation down a ladder formed of both A and B vibrational levels. Formation of N₂(A ³Σ)ν′₂ by atom association and relaxation down the A−B ladder contributes a pressure independent term (above 1 torr) to the intensity of the N₂ 1st positive bands (1+) as suggested by Thrush and Golde. An additional process that involves the ⁵Σ and W ³Δ state, largely populated from N₂(A) via N₂(B), contributes a pressure dependence to the 1+ bands under suitable circumstances and permits population of low ν′ levels of B ³Π even in the absence of collisional energy degradation.