Cold CAS Ion Trap -- 22 pole trap with ring electrodes for astrochemistry

Abstract

The enhancement of a cryogenic radio frequency 22 pole trap instrument by the addition of ring electrodes is presented in detail. The ring electrodes tightly surround the poles and only a fraction of the applied electric potential penetrates to the trap axis, facilitating the fine control of slow cold ions. A precise computational model, describing the effective mechanical potential created by the applied static and rf fields, governing the ion behaviour, is employed to demonstrate and understand the operation of our setup. The use of ring electrodes for improved extraction of cold stored ions is shown. Variable trapping potentials, placed on one ring electrode, can be used to control the evaporation of only those ${\text{H}}^{+}$ ions from the trap, whose kinetic energy exceeds the barrier. This ring electrode trapping opens new possibilities to study processes of minimal kinetic energy release, e. g. spin exchange. We propose a robust modified method for the determination of temperature dependent ion molecule reaction rates, resistant to effects caused by neutral gas freezing and demonstrate it on the reaction of ${\text{CO}}^{+}$/${\text{CO}}_2^{+}$ with ${\text{H}}_2$/${\text{D}}_2$. Finally, the use of a supercontinuum laser for quick localisation of spectroscopic bands is examined on the ${\text{N}}_2^{+}$ Meinel system.

References in corpus (3)

• 2021 Census of Interstellar, Circumstellar, Extragalactic, Protoplanetary Disk, and Exoplanetary Molecules
• The 2014 KIDA network for interstellar chemistry
• Leak-out Spectroscopy, a universal method of action spectroscopy in cold ion traps

Cited by in corpus (8)

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• Measurements and simulations of rate coefficients for the deuterated forms of the H2 + + H2 and H3 + + H2 reactive systems at low temperature
• Infrared Spectroscopy of Pentagon-Containing PAHs: Indenyl and Fluorenyl Anions and Indenyl Cation
• Overtone Transition $2{\nu }_1$ of ${\text{HCO}}^{+}$ and ${\text{HOC}}^{+}$: Origin, Radiative Lifetime, Collisional Quenching
• Rovibrational Overtone and Combination Bands of the HCNH+ Ion
• Cl+ and HCl+ in Reaction with H2 and Isotopologues: A Glance into H Abstraction and Indirect Exchange at Astrophysical Conditions
• Ion-kinetic-energy sampling in a 22-pole trap using ring-electrode evaporation
• Near-infrared high resolution overtone spectroscopy of the hydronium ion H${}_3$O${}^{+}$: the $2{\nu }_3^{2+}$ and $2{\nu }_3^{2-}$ bands