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arXiv · 2410.14832

State Selective Preparation and Nondestructive Detection of Trapped ${\rm O}_2^+$

Ambesh Pratik Singh·Michael Mitchell·Will Henshon·Addison Hartman·Annika Lunstad·Boran Kuzhan·David Hanneke
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Abstract

The ability to prepare molecular ions in selected quantum states enables studies in areas such as chemistry, metrology, spectroscopy, quantum information, and precision measurements. Here, we demonstrate $(2+1)$ resonance-enhanced multiphoton ionization (REMPI) of oxygen, both in a molecular beam and in an ion trap. The two-photon transition in the REMPI spectrum is rotationally resolved, allowing ionization from a selected rovibrational state of O$_2$. Fits to this spectrum determine spectroscopic parameters of the O$_2$ $d\,^1\Pi_g$ state and resolve a discrepancy in the literature regarding its band origin. The trapped molecular ions are cooled by co-trapped atomic ions. Fluorescence mass spectrometry nondestructively demonstrates the presence of the photoionized O$_2^+$. We discuss strategies for maximizing the fraction of ions produced in the ground rovibrational state. For $(2+1)$ REMPI through the $d\,^1\Pi_g$ state, we show that the Q(1) transition is preferred for neutral O$_2$ at rotational temperatures below 50~K, while the O(3) transition is more suitable at higher temperatures. The combination of state-selective loading and nondestructive detection of trapped molecular ions has applications in optical clocks, tests of fundamental physics, and control of chemical reactions.

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Ambesh Pratik Singh, Michael Mitchell, Will Henshon, Addison Hartman, Annika Lunstad, Boran Kuzhan, David Hanneke. 2024-10-18. State Selective Preparation and Nondestructive Detection of Trapped ${\rm O}_2^+$. https://doi.org/10.1063/5.0244447

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