Speaker
Description
Three-body association describes the process where three atoms or molecules collide to form a bound complex between two of them. This process plays a role in a multitude of physical systems, for example ozone formation in the atmosphere, the formation of clusters in supersonic jets, cold and ultracold chemistry and in tagging spectroscopy [1]. Ab initio calculations of three-body association reactions are still challenging and experimental data is needed as a benchmark for theoretical calculations. Three-body association reactions of noble gases have been previously studied using supersonic flow [2], but these measurements are limited by a fixed maximum interaction time in the order of milliseconds. This work aims to measure the reaction rate coefficient inside our cryogenic RF 16-pole wire trap, utilizing the long storage times that can be reached in our trap at lower temperatures [3]. Longer interaction times in turn mean the reaction can be observed at lower densities, which could allow us to measure the lifetime of the meta stable complex [4]. Our group has previously studied the three-body association of $\mathrm{Cl}^-$ with $\mathrm{H}_2$ [5]. Additionally the three-body association rate coefficient for $\mathrm{He}$ is so well studied, by measuring it, we can extract the ion temperature in our trap [6].
[1] M. Mirahmadi and J. Pérez-Ríos, Three-Body Recombination in Physical Chemistry, Int. Rev. Phys. Chem. 41, 233 (2022).
[2] S. Hamon, et al., Low-Temperature Measurements of the Atomic Association Reaction $\mathrm{Ar}^+$ + 2$\mathrm{Ar}$ → $\mathrm{Ar}_2^+$ + $\mathrm{Ar}$, Chem. Phys. Lett. 288, 523 (1998).
[3] C. Lochmann, et al., Three-Body Collisions Driving the Ion–Molecule Reaction $\mathrm{C}_2^-$ + $\mathrm{H}_2$ at Low Temperatures, J. Phys. Chem. A 127, 4919 (2023).
[4] I. Zymak, et al., Ternary Association of $\mathrm{H}^+$ Ion with $\mathrm{H}_2$ at 11 K, Experimental Study, The European Physical Journal Applied Physics 56, 24010 (2011).
[5] R. Wild, et al., Complex Formation in Three-Body Reactions of $\mathrm{Cl}^-$ with $\mathrm{H}_2$, J. Phys. Chem. A 125, 8581 (2021).
[6] R. Plašil, et al., Stabilization of $\mathrm{H}^+$-$\mathrm{H}_2$ Collision Complexes between 11 and 28 K, Phil. Trans. R. Soc. A 370, 5066 (2012).
