PHOTOIONIZATION OF HIGH-TEMPERATURE VAPORS .6. S2,SE2, AND TE2

From the photoionization-efficiency curves of S2, Se 2, and Te2, the thresholds for formation of parent and fragment ions have been determined. The ionization potentials of Se2 and Te2 obtained from these measurements are 8.88±0.03 and 8.29±0.03 eV, respectively. For D00(S2), the value 101.0±0.2 kcal/mole is deduced, in general agreement with other techniques. The result D00(Te2)=62. 3±0.2 kcal/mole distinctly favors one of two proposed thermochemical values. The experimental result D00(Se2) = 78.6-83.2 kcal/mole has considerable uncertainty but tends to favor the highest of three spectroscopic possibilities. Evidence is presented for a 0.35±0.04-eV splitting between the 0g+ ground state of Te2 and the Te2 state.