Isomer-specific product formation in the proton transfer reaction of HOCO⁺ with CO

Abstract

The proton transfer reaction HOCO⁺+CO → HCO⁺/HOC⁺ has been studied using crossed-beam velocity map imaging. Angular and energy differential cross sections were obtained for collision energies from 0.3 to 2.3 eV. Scattering in forward direction together with a prominent scattering angle-dependent internal excitation is found at all collision energies. The exothermic HCO⁺ product appears to be very dominant even at energies above the energy threshold for the formation of metastable HOC⁺ ion. To determine the HOC⁺ contribution for different angular ranges, a model has been developed. We obtain an upper limit for the HOC⁺ product isomer fraction of <2%. In theoretical calculations, we find the CO₂-catalysed isomerisation channel to be energetically accessible. However, it may not have a strong impact on the isomer ratio. Chemical dynamics simulations are needed to shed more light on this question.

Keywords:

• reaction dynamics
• ion–molecule reactions
• astrochemistry
• velocity map imaging
• proton transfer

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Eduardo Carrascosa acknowledges funding by the DOC-scholarship of the Austrian Academy of Sciences (OeAW).