Frankland V L, Rosu-Finsen A, Lasne J, Collings M P, McCoustra M R S
Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom.
Rev Sci Instrum. 2015 May;86(5):055103. doi: 10.1063/1.4919657.
Although several research groups have studied the formation of H2 on interstellar dust grains using surface science techniques, few have explored the formation of more complex molecules. A small number of these reactions produce molecules that remain on the surface of interstellar dust grains and, over time, lead to the formation of icy mantles. The most abundant of these species within the ice is H2O and is of particular interest as the observed molecular abundance cannot be accounted for using gas-phase chemistry alone. This article provides a brief introduction to the astronomical implications and motivations behind this research and the requirement for a new dual atomic beam ultrahigh vacuum (UHV) system. Further details of the apparatus design, characterisation, and calibration of the system are provided along with preliminary data from atomic O and O2 beam dosing on bare silica substrate and subsequent temperature programmed desorption measurements. The results obtained in this ongoing research may enable more chemically accurate surface formation mechanisms to be deduced for this and other species before simulating the kinetic data under interstellar conditions.
尽管有几个研究小组利用表面科学技术研究了星际尘埃颗粒上H2的形成，但很少有人探索更复杂分子的形成。这些反应中有一小部分会产生留在星际尘埃颗粒表面的分子，随着时间的推移，会导致冰幔的形成。冰中这些物种中最丰富的是H2O，特别令人感兴趣，因为仅用气相化学无法解释观测到的分子丰度。本文简要介绍了这项研究背后的天文学意义和动机，以及对新型双原子束超高真空（UHV）系统的要求。文中还提供了该系统的装置设计、表征和校准的进一步细节，以及在裸露的二氧化硅衬底上进行原子O和O2束剂量注入以及随后的程序升温脱附测量的初步数据。在这项正在进行的研究中获得的结果，可能使我们在模拟星际条件下的动力学数据之前，能够推导出关于这种及其他物种的更化学精确的表面形成机制。
