95 research outputs found

    Merged-beams Reaction Studies of O + H_3^+

    Get PDF
    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 Journa

    Recommended Thermal Rate Coefficients for the C + H3+_3^+ Reaction and Some Astrochemical Implications

    Get PDF
    We have incorporated our experimentally derived thermal rate coefficients for C + H3+_3^+ forming CH+^+ and CH2+_2^+ into a commonly used astrochemical model. We find that the Arrhenius-Kooij equation typically used in chemical models does not accurately fit our data and use instead a more versatile fitting formula. At a temperature of 10 K and a density of 104^4 cm−3^{-3}, we find no significant differences in the predicted chemical abundances, but at higher temperatures of 50, 100, and 300 K we find up to factor of 2 changes. Additionally, we find that the relatively small error on our thermal rate coefficients, ∼15%\sim15\%, significantly reduces the uncertainties on the predicted abundances compared to those obtained using the currently implemented Langevin rate coefficient with its estimated factor of 2 uncertainty.Comment: 19 pages, 5 figures. Accepted for publication in Ap

    Expatriation and Incapacity created by a Multitude of Hidden Inequalities

    Get PDF
    The ability of UK based Academics to function within collaborative partnerships is becoming an important part of the UK Universities internationalisation agenda. This chapter offers an auto-ethnographical academic expatriate experience detailing some of the challenges faced when moving to work in a ‘UK environment positioned abroad’, specifically in China. It will provide HR personnel with alternative understandings of possible support strategies that could assist individuals in dealing with a variety of hidden inequalities that surface. These hidden inequalities can contribute to a possible shortening of the assignment due to cultural contexts in which they are operating (Foster 1997; Wang and Varma 2017)

    Agglomeration and Innovation

    Full text link

    How Trade-Restrictive Is Standardized Packaging? Economic and Legal Implications of the WTO Panel Reports in Australia-Tobacco Plain Packaging

    Get PDF
    Published by Cambridge University Press. The lengthy and long-awaited WTO Panel Reports in Australia-Tobacco Plain Packaging contain a host of material for reflection, particularly in relation to the Agreement on Technical Barriers to Trade (TBT) and the Agreement on Trade-Related Aspects of Intellectual Property Rights. While two of the Panel Reports proceed to appeal, we consider with respect to the two adopted Panel Reports the Panel's reasoning in relation to Article 2.2 of the TBT, focusing on the meaning of trade-restrictiveness. This concept central to WTO law has been under-examined to date, and these Panel Reports demonstrate some of the complexities in identifying trade-restrictive measures, particularly where they are non-discriminatory. The Panel found that Australia's measures restrict trade because they contribute to their objective of reducing tobacco consumption. Therefore, any equally effective alternative will similarly restrict trade. This curious result under TBT Article 2.2 may be particular to non-discriminatory measures that target 'socially bad' products such as tobacco
    • …
    corecore