Helium Droplets Doped with Sulfur and C 60 .

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 C ₆₀ . 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 _m ⁺ , S _m ^- , and C ₆₀ S _m ^- containing up to 41 sulfur atoms. We also observe complexes of sulfur cluster anions with helium; distributions are presented for He _n S _m ^- with n ≤ 31 and m ≤ 3. The similarity between anionic and cationic C ₆₀ S _m ^± spectra is in striking contrast to the large differences between spectra of S _m ⁺ and S _m ^- .