Effects of the charge–dipole and charge–quadrupole interactions on the He+ + CO reaction rate coefficients at low collision energies
Open access
Date
2022-11Type
- Journal Article
Abstract
The reaction between He+ and CO forming He + C+ + O has been studied at collision energies in the range between 0 and kB ⋅ 25 K. These low collision energies are reached by measuring the reaction within the orbit of a Rydberg electron after merging a beam of He(n) Rydberg atoms and a supersonic beam of CO molecules with a rotational temperature of 6.5 K. The capture rate of the reaction drops by about 30% at collision energies below kB ⋅ 5 K. This behavior is analyzed in terms of the long-range charge–dipole and charge–quadrupole interactions using an adiabatic-channel capture model. Although the charge–dipole interaction has an effect on the magnitude of the rate coefficients, the effects of the charge–quadrupole interaction determine the main trend of the collision-energy dependence of the rate coefficients at low collision energies. The drop of the capture rate coefficient at low collision energies is attributed to the negative sign of the quadrupole moment of CO (Qzz = −2.839 D Å) and is caused by the |JM⟩ = |00⟩ and |1 ± 1⟩ rotational states of CO, which represent about 70% of the CO molecules at the rotational temperature of 6.5 K. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000580726Publication status
publishedExternal links
Journal / series
New Journal of PhysicsVolume
Pages / Article No.
Publisher
Deutsche Physikalische GesellschaftSubject
Ion-molecule reaction; Cold chemistry; Reaction rate coefficients; Rydberg states; Charge-dipole interaction; Charge-quadrupole interaction; Merged beamsOrganisational unit
03449 - Merkt, Frédéric / Merkt, Frédéric
Funding
200478 - Precision measurements with cold molecules: Rydberg states, ions and photoionization (SNF)
743121 - Cold Ion Chemistry - Experiments within a Rydberg Orbit (EC)
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