Scattering of High-Velocity Neutral Particles. XVII. Ar–O2, Ar–N2, Ar–CO

Fast Ar beams with energies between about 200–1500 eV have been scattered by room‐temperature O₂, N₂, and CO to obtain the following potentials (where the energy is given in electron volts and the interaction distance in angstroms): $$\mathrm{Ar}–{\mathrm{O}}_2{\text{V(r)\hspace{0.17em}=\hspace{0.17em}1.36\hspace{0.17em}×\hspace{0.17em}10}}^3{\mathrm{\hspace{0.17em}/\hspace{0.17em}r}}^{\text{8.34}}\text{2.01\hspace{0.17em}<\hspace{0.17em}r\hspace{0.17em}<\hspace{0.17em}2.50,}$$ $$\mathrm{Ar}–{\mathrm{N}}_2{\text{V(r)\hspace{0.17em}=\hspace{0.17em}567\hspace{0.17em}/\hspace{0.17em}r}}^{\text{7.06}}\text{2.04\hspace{0.17em}<\hspace{0.17em}r\hspace{0.17em}<\hspace{0.17em}2.53,}$$ $$\mathrm{Ar}–\mathrm{CO}{\text{V(r)\hspace{0.17em}=\hspace{0.17em}551\hspace{0.17em}/\hspace{0.17em}r}}^{\text{6.99}}\text{2.09\hspace{0.17em}<\hspace{0.17em}r\hspace{0.17em}<\hspace{0.17em}2.68.}$$ Results for these systems in the indicated ranges have not been previously reported from this laboratory. They are, however, in quite satisfactory agreement with independent measurements of Leonas and coworkers in Moscow, and show that even at the small separation distances involved in these high energy collisions, the average force fields on N₂ and CO are essentially identical. The peripheral‐force approximation, which assumes that the centers of force in a molecule are located at the nuclei of each atom, has been used to construct the individual atom–atom interactions which combine to make up the experimental atom–molecule potentials. In the one case where direct scattering measurements are available, the Ar−O system, agreement between the derived and experimental atom–atom potentials is excellent. Potentials have also been derived for the following atom‐molecule and molecule‐molecule systems by continuing the peripheral‐force approximation with established semiempirical combination rules: N–N₂; N–O₂; N–NO; O–O₂; O–N₂; O–NO; N₂–N₂; O₂–N₂; O₂–O₂; N₂–NO; O₂–NO; and NO–NO. With the exception of molecule–molecule systems involving NO there is good agreement between the derived potentials and those obtained directly from scattering experiments. There is also reasonable agreement, considering the limitations of the models, between the derived potentials and theoretical calculations for systems where it is possible to make comparisons.