Laboratory Astrophysics of Interstellar Ice Mantles

奖项编号：AST -0807832研究机构：弗吉尼亚大学主校区PI：Raul A Baragiola标题：实验室星际冰地幔天体物理学这项研究将解决气体分子和暗星际分子云中尘埃颗粒之间的平衡问题，这是星际物质演化中未解决的核心问题之一。问题包括：由于分子云的低温和高冷凝系数，所有的气态物质，除了H2和He，都会在通常10万年的时间内通过冷凝在颗粒上而耗尽。然而，一个典型的分子云的寿命要长得多，数百万年，并且包含相对大量的气相分子。因此，必须运行有效的解吸机制。然而，没有一个提出的机制可以令人信服地保持观察到的气体群体。为此，在这里进行的实验室研究进行了新的实验，以确定解吸率，由于：a）光解吸紫外线莱曼α光子，B）热解吸氢原子的重组成氢分子吸附在冰，c）解吸从解离电子附着引起的低能电子。此外，由于分子云中的主要星际气体是分子氢，分子氢很容易被微孔水冰吸收，因此实验将模拟这些条件，研究H2吸附，通过吸附CO等其他气体取代H2，以及吸附的氢对水冰中光解吸和分子光合作用的影响。这项研究将使用高灵敏度的微重力和质谱技术来测量冰在低温真空中的解吸。该研究小组展示了研究领域的专业知识，并通过将其他科学领域的知识和技术应用于天文问题来促进创新，例如低能电子解吸将在分子云中发生的新概念。除了天文应用的研究，辐射处理的材料的理解在这里开发的应用在半导体，薄膜和化学工业。Baragiola博士正在与科学家合作研究其中的一些应用。学生将积极参与这项研究，这将为学生提供培训，使他们为工业，政府和学术职业道路做好准备。一些研究也将被纳入本科天文学入门课程，部分是为了帮助学生了解实验室天体物理学在我们不断探索了解我们的宇宙中所起的作用。

AWARD NO: AST - 0807832INSTITUTION: University of Virginia Main CampusPI: Raul A BaragiolaTITLE: Laboratory Astrophysics of Interstellar Ice MantlesThis research will address the question of the balance between molecules in the gas and on dust grains in dark interstellar molecular clouds, one of the central unsolved problems in the evolution of interstellar matter. The problem consists of the following: due to the low temperature of molecular clouds and high condensation coefficients, all gaseous species, with the exception of H2 and He would be depleted by condensation on grains, in times of typically 100,000 years. Yet a typical molecular cloud lives much longer, millions of years, and contains a relatively high number of molecules in the gas phase. Therefore, an efficient desorption mechanisms must operate. However, none of the proposed mechanisms can convincingly maintain the gas population observed. For this reason, the laboratory studies to be undertaken here perform novel experiments to determine desorption rates due to: a) photodesorption by ultraviolet Lyman-alpha photons, b) thermal desorption by recombination of H atoms into H2 molecules adsorbed on ices, c) desorption from dissociative electron attachment caused by low energy electrons. In addition, since the main interstellar gas in molecular clouds is molecular hydrogen, which can be readily absorbed in microporous water ice, the experiments will simulate those conditions, studying H2 adsorption, replacement of H2 by adsorption of other gases such as CO, and the effect of adsorbed hydrogen on the photodesorption and molecular photosynthesis in water ice. The research will use highly sensitive techniques of microgravimetry and mass spectrometry to measure desorption of ices at cryogenic temperatures in ultrahigh vacuum. The research group has demonstrated expertise in the research area and promote innovation by applying knowledge and techniques from other areas of science into astronomical problems, such as the new concept that desorption by low energy electrons will occur in molecular clouds. In addition to the astronomical applications of the research, the understanding of radiation processing of materials developed here has applications in semiconductor, thin film and chemical industries. The Dr. Baragiola is collaborating with scientists on some of these applications. Students will be active participants in this research which will provide training for students that will prepare them for industrial, government and academic career paths. Some of the research will also be incorporated into undergraduate introductory astronomy courses in part to help students understand the role laboratory astrophysics plays in our ongoing quest to understand our universe.