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MO: Fachverband Molekülphysik

MO 10: Collisions (joint session MO/Q)

MO 10.2: Vortrag

Mittwoch, 8. März 2023, 14:45–15:00, F142

Dissociative recombination of ArH⁺ at the Cryogenic Storage Ring — •Ábel Kálosi^1,2, Manfred Grieser², Leonard W. Isberner^3,2, Daniel Paul^1,2, Daniel W. Savin¹, Stefan Schippers³, Viviane C. Schmidt², Andreas Wolf², and Oldřich Novotný² — ¹Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA — ²Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany — ³I. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany

ArH⁺ is an important probe of the cosmic ray flux in interstellar space. Cosmic rays are the dominant ionization source for H and H₂ in the cold interstellar medium (ISM). This ionization initiates astrochemistry in the cold phases of the ISM. The cosmic ray ionization rate (CRIR) is thus an important parameter for both chemical and dynamical models of the ISM. ArH⁺ forms via cosmic ray ionization of Ar, but can be destroyed via dissociative recombination (DR) with free electrons. Astronomical observations of ArH⁺, combined with chemical models, enable one to quantitatively estimate the CRIR. Such models require reliable rate coefficients that take into account the low internal excitation of the ArH⁺, as occurs in the cold ISM. To this end, we have performed merged-beams DR experiments with ArH⁺ in the Cryogenic Storage Ring where, at an ambient temperature of ∼ 10 K, the ions relaxed to their lowest rotational states.