Energy transfer mechanisms in backward scattering of Cs+ ions from N2 molecules

The energy transfer processes in Cs⁺-N₂ collisions were experimentally studied at laboratory (lab) collision energies Elab=50-2500.16em0exeV and lab scattering angles θ>2^∘ via differential scattering spectroscopy. A classical trajectory calculation method was used to analyze the experimental results. We observed specific electronic excitations to the Cs⁺+N₂(A³Σ) and Cs⁺+N₂(a¹Π) states in the energy-transfer spectra with significant excitation probabilities in backward scatterings at lower center-of-mass (CM) energies E=13.6-18.30.16em0exeV (Elab=78-1050.16em0exeV) and a CM angle Θ~165^∘ (θ=5^∘). The results of the simulations of energy transfer spectra through classical trajectory calculations indicate that electronic transitions occur around the molecular orientation γ=π/2 and at vibrotational excitation energies ΔE/E<0.12. The potential crossings for the N₂(A³Σ) and N₂(a¹Π) excitations are located at the intermolecular potentials of VIM(R,γ=π/2)=13.4 and 16.4 eV, respectively. N₂(A³Σ) excitation is the dominant electronic excitation process at lower energies of E<17.50.16em0exeV (Elab<1000.16em0exeV). Evaluations using an empirical charge-overlap model reasonably reproduce intermolecular potential crossings. Moreover the proposed model can provide effective information on the spin-changing N₂(A³Σ) excitation.