Electronic-energy exchange cross sections for Ar* (3P) and N2(X 1Σg+)

Differential cross sections for Ar* (³P) scattered by ${\mathrm{N}}_2{\mathrm{(X\hspace{0.17em}}}^1{\Sigma }_g^{+})$ , obtained at 0.051 eV using crossed molecular beams, are reported from 4° to 174° c.m. A rainbow maximum is observed at 6.3° c.m. The small‐angle elastic scattering is analyzed to obtain parameters for a double‐Lennard‐Jones potential. At large angles the cross sections are depleted by exchange scattering. The exchange probabilities are obtained by subtracting the experimental cross sections from elastic scattering cross sections calculated from the double‐Lennard‐Jones parameters. The resulting total exchange cross section and threshold energy are σ_ex = 11.8±3.5 Å, E₀=0.0081±0.001 eV. Comparison with cross sections deduced from published rate constants indicates that σ_ex increases with initial relative kinetic energy from threshold to 0.051 eV.