Gas phase antimony/tungsten/oxygen cluster cations

Sb/W/O cluster ions were produced using a gas-aggregation source and were investigated by time-of-flight mass spectrometry following ionization with a 266-nm YAG laser. A W-heater in the presence of O2 gas and Sb vapor reacted to produce the Sb/W/O species, followed by ionization and fragmentation to produce stable cluster ions which could be observed in mass spectra. Two series of cluster ions, (Sb3O4)(WO3)n+ and (Sb5O7)(WO3)n+, were found to be stable along with cluster ions with a balanced count of free valence electrons. The cluster structures were estimated by density-functional calculations.