Molecular beam photoionization study of S2

Higher resolution photoionization efficiency data for the formation of S+2 and S+ from S2 in the wavelength region of 600–1350 Å have been obtained using the supersonic oven beam method. The ionization energy (IE) of S2 is determined to be 9.356±0.002 eV (1325.2±0.3 Å). The measured appearance energy of 14.732±0.005 eV (841.6±0.3 Å) for the dissociative ionization process S2+hν→S++S+e−, together with the IE of S2, yields a value of 5.376±0.005 eV for the bond dissociation energy of S+2. Two Rydberg series converging to the b̃ 4Σ−g state (13.20 eV) of S+2 are observed. Window resonances resolved in the wavelength region of 670–850 Å are assigned as members of the Rydberg series converging to the c̃ 4Σ−u (17.70 eV) and 2Πu (or 2Σ−u) (18.66 eV) states of S+2.