Lifetime of K+– heavy Rydberg states formed by electron transfer in K(np)-SF6 collisions

At low n (n < 15–20), electron transfer in collisions between K(np) Rydberg atoms and SF6 can lead to formation of bound K+– SF 6 - ion pairs that orbit at relatively large separations. A fraction of such ion pairs subsequently dissociate through conversion of internal energy in the SF 6 - ions to translational energy of the ion pair. The lifetimes of these ion pairs are measured by observing their dissociation. The data show that while the majority of the ion pairs have lifetimes of ∼1 μs, some can have lifetimes of 5 μs or longer, much greater than their anticipated orbital periods, ∼20–150 ps.