English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We have measured the reaction of O + H3+ forming OH+ and H2O+. This is one ofthe key gas-phase astrochemical processes initiating the formation of watermolecules in dense molecular clouds. For this work, we have used a novel mergedfast-beams apparatus which overlaps a beam of H3+ onto a beam of ground-termneutral O. Here, we present cross section data for forming OH+ and H2O+ atrelative energies from \approx 3.5 meV to \approx 15.5 and 0.13 eV,respectively. Measurements were performed for statistically populated O(3PJ) inthe ground term reacting with hot H3+ (with an internal temperature of \approx2500-3000 K). From these data, we have derived rate coefficients fortranslational temperatures from \approx 25 K to \approx 10^5 and 10^3 K,respectively. Using state-of-the-art theoretical methods as a guide, we haveconverted these results to a thermal rate coefficient for forming either OH+ orH2O+, thereby accounting for the temperature dependence of the O fine-structurelevels. Our results are in good agreement with two independent flowingafterglow measurements at a temperature of \approx 300 K, and with acorresponding level of H3+ internal excitation. This good agreement stronglysuggests that the internal excitation of the H3+ does not play a significantrole in this reaction. The Langevin rate coefficient is in reasonable agreementwith the experimental results at 10 K but a factor of \approx 2 larger at 300K. The two published classical trajectory studies using quantum mechanicalpotential energy surfaces lie a factor of \approx 1.5 above our experimentalresults over this 10-300 K range.

Merged-beams Reaction Studies of O + H_3^+