The formation, photodissociation, and bond structure of cobalt–sulfur cluster ions

The formation and photodissociation of cobalt–sulfur cluster ions (ConS+m) produced by laser ablation on a tablet of well-mixed cobalt and sulfur powder were studied with a home-built tandem time-of-flight (TOF) mass spectrometer. In the mass spectrum, there are many intense peaks of more stable cluster ions ConS+m signified as follows: n=2–5,7, m=n−1; n=6,8–11, m=n−2; n=12–13, m=n−3; n=14–16, m=n−4. The photolysis of the mass-selected cluster ions was performed with a 248 nm excimer laser. The dissociation patterns support the above composition results. Previous theories about clusters do not explain the experimental results. A relationship between the electron number and orbital number of more stable clusters was recognized. Ab initio calculations were performed on two small cluster ions to determine stable geometries.