Investigation of the Formation of Molecular Hydrogen, Hydrocarbons and Nitriles on the Surface of Aerosol Analogues of Titan Atmosphere

AST 0507405VidaliDr.来自锡拉丘兹大学的维达利和皮罗内洛博士将研究在模拟土卫六环境的条件下分子的形成。目的是研究在低压环境中的物理和化学过程，如在泰坦的高大气中形成气溶胶颗粒，以及在较高压力环境中，凝结材料的暴露表面由气溶胶颗粒沉淀而成。Vidali博士的实验室率先使用表面/低温物理技术研究尘埃颗粒类似物上分子氢的形成和H2O覆盖的CO冰的氧化反应，他的团队的经验可以卓有成效地用于研究泰坦环境中发生的类似过程。最重要的问题之一是在平流层水平上去除非常活泼的氢原子，这些氢原子使乙炔等不饱和物质形成并存活下来。Vidali和Pirronello博士的团队将测量有机表面上的H2形成效率;在Titan上，这些表面可能通过连续的光处理保持在反应状态。其他需要研究的重要表面反应包括由N2和CH 4的光分解产生的自由基，这是泰坦大气中最丰富的物质。与H2形成过程中发生的情况相反（最终产物物质被除去），与其他自由基反应的产物可能保留在表面上，丰富了固相的化学复杂性。这些实验的预期结果将有助于行星科学家解释卡西尼/惠更斯使命即将获得的数据。 这项研究的潜在影响可能是重大的，因为，加上卡西尼/惠更斯使命提供的数据，这里详细介绍的研究工作应能对地球以外的行星体的大气组成和演变产生前所未有的看法和了解。从教育的角度来看，它为本科生和研究生提供了在跨学科领域工作的机会，该领域处于天体物理学，行星科学和表面科学研究的最前沿。 ***

AST 0507405VidaliDr. Vidali and Dr. Pirronello, of Syracuse University, will investigate the formation of molecules in conditions that simulate Titan's environment. The aim is to study physical and chemical processes both in low pressure environments, as in Titan's high atmosphere where aerosol particles form, and in a higher pressure environment where exposed surfaces of condensed material are made by the precipitation of aerosol particles. Dr. Vidali's laboratory has pioneered the use of surface/low temperature physics techniques in the study of the formation of molecular hydrogen on dust grain analogues and in oxidation reaction of H2O-capped CO ice, and the experience of his group can fruitfully be used to investigate similar processes occurring in Titan's environments. One of the most important problems is connected with the removal at the stratospheric level of the very reactive hydrogen atoms that allow unsaturated species like acetylene to form and survive. Drs. Vidali and Pirronello's group will measure the H2 formation efficiency on organic surfaces; on Titanthese surfaces are probably maintained in a reactive state by continuous photo-processing. Other important surface reactions to be investigated involve radicals produced by the photodissociation of N2 and CH4, the most abundant species in Titan's atmosphere. Contrary to what happens in the formation of H2 (which ends up with the removal of the product species), the products of reactions with other radicals probably remain on the surface enriching the chemical complexity of the solid phase. The expected results of these experiments will help planetary scientists interpret forthcoming data from the Cassini/Huygens mission. The potential impact of this research can be significant, since, together with data coming from the Cassini/Huygens mission, the research work detailed here should yield an unprecedented view and understanding of the composition and evolution of the atmosphere of a planetary body besides the Earth. From the educational point of view, it offers both undergraduate and graduate students an opportunity to work in an interdisciplinary field which is at the forefront of research in astrophysics, planetary science and surface science. ***