تقرير
Merged-beams Reaction Studies of O + H_3^+
| العنوان: | Merged-beams Reaction Studies of O + H_3^+ |
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| المؤلفون: | de Ruette, N., Miller, K. A., O'Connor, A. P., Urbain, X., Buzard, C. F., Vissapragada, S., Savin, D. W. |
| سنة النشر: | 2015 |
| المجموعة: | Astrophysics Physics (Other) |
| مصطلحات موضوعية: | Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Atomic Physics |
| الوصف: | We have measured the reaction of O + H3+ forming OH+ and H2O+. This is one of the key gas-phase astrochemical processes initiating the formation of water molecules in dense molecular clouds. For this work, we have used a novel merged fast-beams apparatus which overlaps a beam of H3+ onto a beam of ground-term neutral O. Here, we present cross section data for forming OH+ and H2O+ at relative energies from \approx 3.5 meV to \approx 15.5 and 0.13 eV, respectively. Measurements were performed for statistically populated O(3PJ) in the ground term reacting with hot H3+ (with an internal temperature of \approx 2500-3000 K). From these data, we have derived rate coefficients for translational 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 have converted these results to a thermal rate coefficient for forming either OH+ or H2O+, thereby accounting for the temperature dependence of the O fine-structure levels. Our results are in good agreement with two independent flowing afterglow measurements at a temperature of \approx 300 K, and with a corresponding level of H3+ internal excitation. This good agreement strongly suggests that the internal excitation of the H3+ does not play a significant role in this reaction. The Langevin rate coefficient is in reasonable agreement with the experimental results at 10 K but a factor of \approx 2 larger at 300 K. The two published classical trajectory studies using quantum mechanical potential energy surfaces lie a factor of \approx 1.5 above our experimental results over this 10-300 K range. Comment: 43 pages, 11 figures. Submitted to the Astrophysical Journal |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/0004-637X/816/1/31 |
| URL الوصول: | http://arxiv.org/abs/1508.07882 |
| رقم الأكسشن: | edsarx.1508.07882 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/0004-637X/816/1/31 |
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