Vibrationally Inelastic Collision Between Li₂(ν = 0) and Li: Direct and Postponed Elongation Mechanisms

The mechanism for vibrational inelastic excitation during the collision between Li₂(ν = 0) and Li was investigated exploiting classical trajectory simulations over a potential energy surface generated by fitting valence full configuration interaction calculations employing a large basis set. From the trajectory results, it emerges that the vibrational excitation in noncapture collisions presents uniquely a forward-scattered projectile for the highest levels of excitation (Δ<i>E</i>(0 → ν′) ≃ E_coll). For lower ν′, a minor contribution presenting a backward-scattered projectile appears, which, however, has its major contribution coming from a “slingshot”-like (orbiting) mechanism exploiting the attractive features of the Li₃ potential energy surface rather than a direct recoil