Formation of doubly positively charged diatomic ions of Mo ₂ ²⁺ produced by Ar ⁺ sputtering of an Mo metal surface

The formation of diatomic ions of Mo ²⁺ ₂ formed during Ar ⁺ sputtering of an molybdenum metal surface, was investigated. A secondary ion mas spectrometer was used to study the diatomic dications in the positive ion mass spectra. It was found that the the diatomic ions of Mo ²⁺ ₂ were observed at high primary current densities for projectile ions of Ar ⁺. The formation of the dications was found to take place by resonant charge transfer in grazing gas-phase collisions between incoming projectile ions of Ar ⁺ and sputtered molecular ions of Mo ²⁺ ₂.