Trapping, cooling, and photodissociation analysis of state-selected H$\_2^+$ ions produced by (3+1) multiphoton ionization

Abstract

We report on the production of cold, state-selected H + 2 molecular ions in a linear RF trap. The ions are produced by (3+1) resonance-enhanced multi-photon ionisation (REMPI) of H2, and sympathetically cooled by laser-cooled Be + ions. After demonstrating and characterizing the REMPI process, we use photodissociation by a deep UV laser at 213 nm to verify the high vibrational purity of the produced H + 2 ion samples. Moreover, the large difference between the photodissociation efficiencies of ions created in the v = 0 and v = 1 levels provides a way to detect a v = 0 → 1 transition. These results pave the way towards high-resolution vibrational spectroscopy of H + 2 for fundamental metrology applications.