Helium Droplets Doped with Sulfur and C₆₀

Clusters of sulfur are grown by passing superfluid helium nanodroplets through a pickup cell filled with sulfur vapor. In some experiments the droplets are codoped with C₆₀. The doped droplets are collided with energetic electrons and the abundance distributions of positively and negatively charged cluster ions are recorded. We report, specifically, distributions of S ⁺, S ^-, and C₆₀S ^- containing up to 41 sulfur atoms. We also observe complexes of sulfur cluster anions with helium; distributions are presented for He S ^- with n ≤ 31 and m ≤ 3. The similarity between anionic and cationic C₆₀S ^± spectra is in striking contrast to the large differences between spectra of S ⁺ and S ^-.