Formation and photodepletion of cluster ion–messenger atom complexes in a cold ion trap: Infrared spectroscopy of VO⁺, VO⁺₂, and VO⁺₃

A novel experimental technique is described in which radiation from a free electron laser is used to measure infrared spectra of gas-phase cluster ions via vibrational predissociation of the corresponding ion–messenger atom complexes. The weakly bound complexes are formed in a temperature-controllable, radio frequency ion trap. This technique is applied to the study of the vibrational spectroscopy of the monovanadium oxide cluster cations VO+, VO+2, and VO+