Transition Probabilities and Collision Broadening Cross Section of the N2 Lyman–Birge–Hopfield System

Bands of the N₂ Lyman–Birge–Hopfield system ${\mathrm{(a}}^1{\Pi }_g{\mathrm{\hspace{0.17em}-\hspace{0.17em}X}}^1{\Sigma }_g^{+})$ have been observed in absorption in path lengths ranging from 5.6 × 10⁻³ to 0.5 m·atm. Comparison of theoretical and measured curves of growth and band profiles have allowed the computation of band transition probabilities, lifetimes of the $a^1{\Pi }_g$ state ${\text{[τ(0)\hspace{0.17em}=\hspace{0.17em}1.4\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−4}}\sec ]$ , relative probabilities of electric quadrupole and magnetic dipole components, and a measure of the collision self‐broadening cross section ${\text{(σ\hspace{0.17em}=\hspace{0.17em}1.6\hspace{0.17em}×\hspace{0.17em}10}}^{\text{−14}}{\mathrm{cm}}^2)$ .