Incomplete rotational cooling in a 22-pole ion trap

Abstract

Cryogenic 22-pole ion traps have found many applications in ion-molecule reaction kinetics and in high resolution molecular spectroscopy. For most of these applications it is important to know the translational and internal temperatures of the trapped ions. Here, we present detailed rotational state thermometry measurements over an extended temperature range for the two ion/buffer gas systems OH-/He and OD-/HD with ion-to-neutral mass ratios of 4.25 and 6 respectively. The measured rotational temperatures show a termination of the thermalisation with the buffer gas around 25K, independent of mass ratio and confinement potential of the trap. Different possible explanations for this incomplete thermalisation have been investigated, among them the thermalisation of the buffer gas and the heating due to room temperature blackbody radiation and room temperature gas entering the trap.

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Cited by in corpus (9)

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• Correcting symmetry imperfections in linear multipole traps
• Investigating the electronic properties and structural features of MgH and of MgH${}^{-}$ anions
• Reassigning the CaH${}^{+}$ 1${}^1\Sigma \to$ 2${}^1\Sigma$ vibronic transition with CaD${}^{+}$
• Temperature-dependent rotationally inelastic collisions of OH- and He
• Ion-kinetic-energy sampling in a 22-pole trap using ring-electrode evaporation