State selective preparation and non-destructive detection of trapped O₂⁺

The ability to prepare and control the quantum state of molecular ions has applications in chemistry, metrology, spectroscopy, quantum information, and tests of fundamental physics. This talk will discuss the initial state preparation of trapped molecular ions, with a focus on resonance-enhanced multi-photon ionization (REMPI) and strategies for producing the oxygen molecular cation O₂⁺ in its rovibrational ground state. Fluorescence mass spectrometry nondestructively demonstrates the trapping of photoionized O₂⁺. The long-term applications of these state-prepared molecules include optical clocks based on molecular vibrations and probes of new physics.