Formation of long-lived C60− ions in Rydberg atom-C60 collisions

Studies of collisions between C60 and K(np) Rydberg atoms with 35 ⩽ n ⩽ 125 indicate that C60 can attach very-low-energy electrons to form long-lived C60− ions. The rate constant for negative ion formation is observed to be small, ≈ 10−8 cm3 s−1, and to be independent of n pointing to s-wave capture. Possible mechanisms for this are discussed, including the formation of image-charge-bound C60− ions.