Molecular-ion trap-depletion spectroscopy of BaCl⁺

Abstract

We demonstrate a simple technique for molecular-ion spectroscopy. BaCl + molecular ions are trapped in a linear Paul trap in the presence of a room-temperature He buffer gas and photodissociated by driving an electronic transition from the ground X 1Σ+ state to the repulsive wall of the A 1Π state. The photodissociation spectrum is recorded by monitoring the induced trap loss of BaCl+ ions as a function of excitation wavelength. Accurate molecular potentials and spectroscopic constants are determined. A comparison of the theoretical photodissociation cross sections with the measurements shows excellent agreement. This study represents an important step toward the production of ultracold ground-state molecular ions. © 2011 American Physical Society.