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How do complex molecules escape from ice grains into deep space?

来源：
报告题目   How do complex molecules escape from ice grains into deep space?
报告人   Prof. David H. Parker
报告人单位   China and Radboud University, the Netherlands
报告时间   2025-04-28 14:30:00
报告地点   物质科研B楼B1502会议室
主办单位   合肥微尺度物质科学国家研究中心
报告介绍

Abstract：

　　In the near-perfect vacuum of the Inter-Stellar Medium (ISM) a wide variety of complex organic molecules, including pre-biotics, are observed, which should have been frozen onto surfaces of dust grains at their thermal temperature of ~15K [1].  Complex molecules are most likely formed when mixtures of solid-phase small molecules covering dust grains are exposed to bond-breaking vacuum ultraviolet radiation [2].  How do the new molecules get free of the ice mantles?  Despite the importance and apparent simplicity of this question, very little information pertaining to the molecular-scale mechanism of desorption from molecular ice is available, due to the experimental and theoretical complexity of condensed phase dynamics [3].   In this talk, special aspects [4] of the velocity map imaging [5] method, which has revolutionized gas-phase research [6], will be exploited to reveal the mechanism for VUV photon induced desorption of the fragile molecule ozone formed by photochemistry at a molecular oxygen surface.  Relevance of our method to astrochemical conditions, and to studies of other molecular ice systems will be discussed.

1.      E. F. van Dishoeck, Astrochemistry of dust, ice and gas: introduction and overview. Faraday Discussions 168, 9 (2014).

2.      K. I. Oberg, Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules. Chem Rev 116, 9631 (2016).

             3.      D. J.  Auerbach, J. C. Tully,  A. M. Wodtke, Chemical dynamics from the gas-phase to surfaces, Nat. Sciences 1, 1 (2021).

             4.      D. A. Chestakov, S.-Min Wu, G.-R. Wu, D. H. Parker, A. T. J. B. Eppink, T. N. Kitsopoulos, Slicing Using a Conventional Velocity Map Imaging Setup:  O2, I2, and I2+ Photodissociation. J Phys Chem A 108, 8100 (2004).

5.      A. T. Eppink, D. H. Parker, Velocity map imaging of ions and electrons using electrostatic lenses: Application in photoelectron and photofragment ion imaging of molecular oxygen. Rev Sci Instr 68, 3477 (1997).

             6.      D. W. Chandler, P. L. Houston, D. H. Parker, Perspective: Advanced particle imaging, J. Chem. Phys. 147, 013601 (2017).

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